Section XIV PREVENTIVE MAINTENANCE SERVICES
50. GENERAL
Preventive maintenance services, as prescribed by Army Regulations, are a function of using organization echelons of maintenance. These services consist of:
a. Before, during, and after operation services performed by the firers and assistants.
b. Scheduled services performed by organizational maintenance personnel (service when filling and charging, and service after six firing missions).
51. BEFORE-OPERATION SERVICE OF TANK GROUP.
The following services are to be performed before filling, charging, and loading the flame thrower with pressure, fuel, and ignition cylinder:
a. Pressure-tank valve. Open and close pressure-tank valve to test for ease of operation.
b. Threaded connections. Check all threaded connections for tightness, using appropriate wrenches.
c. Tank coupling. Examine coupling for cleanliness and ease of movement of lock and cams. ([Par 70]) Clean if necessary. If washer is broken, replace, using screw driver to pry out.
d. Plugs. Check filling plug and safety-head plug for completeness of parts ([Par 69 a]) and cleanliness of threads and seats. Clean, if necessary, with cloth. If rod or rod and chain have broken off and fallen in tank, turn tank upside down and remove. Remove deflector tube from head (using hand, not wrench). Inspect to see if diaphragm is intact. If diaphragm is ruptured, replace the safety head with an unbroken head. ([Par 69 b, c]) Reassemble plug, head, and deflector tube in left fuel tank. ([Fig 11]) Tube should face to rear and at a 45-degree angle to operator’s left shoulder. ([Fig 18]) Screw in deflector tube by hand; do not use wrench on deflector tube. Tighten lock nut with wrench.
e. Pressure-tank clamp. The clamp should hold the pressure tank tightly in place. If tank is loose, a wooden splint or wedge under the clamp may be used as a temporary expedient.
f. Carrier-frame bolts. Check tightness. Use wrench.
g. Carrier. ([Par 71]) Examine all canvas, webbing, and cord for signs of mildew, rot, or wear. Replace defective parts. Move flame thrower to dryer storage if mildew occurs.
h. Cord (lashing). Check for tightness. If necessary, make tighter and use secure, slip-proof knots. When the tank group is filled with fuel and adjusted on the firer, its weight should be carried chiefly by the canvas and webbing, not by the metal frame.
i. Shoulder and body straps. Adjust straps to fit firer. (Pars [19] and [71]) A loose tank group can cause discomfort or injury when the wearer changes positions while on a mission. Check presence and condition of the two pins and two cotter pins which hold shoulder straps to steel support. Check fasteners.
52. BEFORE-OPERATION SERVICE OF GUN GROUP.
The following services are to be performed before filling, charging, and loading with pressure, fuel, and ignition cylinder:
a. Hose nipple, tank end. Examine to be sure nipple is clean and not badly nicked. If badly nicked, the nipple may not make a tight seal at the tank coupling. A leak and loss of pressure may result. See Paragraph [73 d] for repair of the nipple.
b. Fuel hose. Examine surface of hose for cracks or other signs of deterioration. Special attention should be paid to portions adjacent to the gun and tank coupling, which are subjected to severe flexing. If hose is defective, replace. ([Par 73 b, c]) Do not patch.
c. Hose nipple, gun end. Check tightness of threaded connection between hose and fuel-valve body, using hand or very light wrench pressure.
d. Shield. Remove ignition shield. Check cleanliness of threads on shield and on ignition-head body. If not clean, use cloth. When reassembling ([Par 18 c]), shield should turn freely until it locks in correct position.
e. Valve lever and needle.
(1) There should be some play in the valve lever. To test, remove ignition shield. Compress grip safety and valve lever slowly, observing the motion of the valve needle. The valve lever should move approximately 1/16 inch before the needle begins to move.
(2) Valve needle should be seated firmly in the barrel nozzle. After the valve lever is pulled back and released, no play should occur in the needle. For adjustment of needle, see Paragraph [75 d].
f. Screws. Use screw driver to test tightness of all screws.
g. Spring retainer and plug. Check tightness of spring retainer and plug ([Fig 47]) by using hand or very light wrench pressure.
h. Ignition head. All exposed surfaces of the shield, nozzle, needle, and other parts of the ignition head, or adjacent to it, should be clean. If not, use cloth.
i. Atomizer hole. With the fuel valve held fully open, insert a fine wire in the atomizer hole of the nozzle to clean the hole. Then use cloth-wrapped splint to remove from the inside of the nozzle any foreign matter pushed through the atomizer hole. If such matter is not removed, it may interfere with the closing of the fuel valve needle at the nozzle. Repeat procedure in [e (2)] above.
j. Spring case. Spring case should turn freely on ignition head. If it does not, clean any grease or dirt from, surfaces with cloth and relubricate. ([Par 49])
k. Trigger. Pull trigger once or twice to find whether it operates easily and whether it returns to position. If not, clean and lubricate trigger. ([Par 49]) Check condition of trigger spring.
l. Trigger rod. Check position of the trigger rod when trigger is pulled back all the way as when firing. The rod should extend approximately 1/16 inch beyond the end of the lug in the ignition head. If it does not, bend the rod slightly, reverse position of bearing, or replace worn parts.
53. SERVICE WHEN FILLING AND CHARGING.
a. Inspection of fuel tanks. Just before filling and charging, remove plugs ([Par 69 b]) and examine interior of fuel tanks to see whether they are clean and free from foreign matter. If not clean, flush with gasoline until clean.
b. Fuel level. When filling (Pars [37] through [40]), see that fuel reaches the same level in both tanks. If leveling does not occur, the tank connector may be clogged with foreign matter. If so, clean, as in a, above. After filling, wipe plug seats with a cloth before replacing plugs. Wipe any spilled fuel from weapon.
c. Pressure-tank valve. Before charging the tank group with air or nitrogen, open and close the pressure-tank valve several times by hand to be sure it operates freely. If it does not, adjust as described in Paragraph [66 d].
Fig 32. Testing pressure tank and valve, using 0-3,000-pound testing gage from service kit.
d. Testing for leaks in pressure system. After charging, and as few hours as possible before a mission, use an 0-3,000-pound gage furnished in service kit to test pressure. ([Fig 32]) To install gage, unscrew check-valve cap and screw gage in check-valve body. If pressure has fallen below that to which the tank was charged ([Par 32]), a leak is indicated. Remove gage, replace check-valve cap, and check for leaks at joints between pressure tank and valve and between tank valve and check valve. (A wrench should be used to tighten cap on check-valve body so as to avoid producing an additional leak.) Large leaks can be felt or heard. Small leaks can be detected by coating joints with soap-and-water solution. Bubbles indicate leaks. If a leak is revealed between pressure tank and pressure-tank valve, or between check valve and pressure-tank valve, replace all three as a unit. If tests do not show up the leak the tank may have been improperly charged. It should be recharged and then retested.
54. SERVICE WHEN FIRING.
a. Failure to ignite. Pull trigger repeatedly. If ignition cylinder still fails to ignite, dirt may be wedged in ignition head. Unscrew shield one-half turn. Screw it back, rapping shield with the hand while turning. This should dislodge foreign matter. Pull trigger again. Repeat procedure, if necessary.
b. Safety head “blows” (breaks). If safety head breaks, firing mission cannot be carried out. On return, have head replaced. ([Par 69]) Follow test procedure. ([Par 56 b])
55. SERVICE AFTER FIRING.
a. Unloading. Remove ignition cylinder ([Par 30]), close pressure-tank valve, and blow out remaining fuel and pressure. ([Par 30])
b. Removal of equipment. Release the body straps, then the shoulder straps. If prone, lie on side and allow tank group to roll off onto ground. If standing or kneeling, take care that tank group does not drop on feet or legs.
c. Correcting or reporting. Correct any failures or difficulties or report them as soon as possible to service or maintenance personnel.
d. Gun. Remove shield ([Par 18]) and clean interior of shield with cloth. Clean holes in shield with wire or wooden splint. Clean external surfaces of barrel, nozzle, needle, and other parts. Check cleanliness and adjustment of needle. ([Par 75 d]) Check trigger for operation. Lubricate. ([Par 49])
e. Fuel tanks and passages. Remove plugs ([Par 69 b]). Drain any remaining fuel. Use gasoline to remove residues of thickened fuels before they have a chance to harden and obstruct passages. If necessary, fill tanks with gasoline and allow to stand for several hours, shaking occasionally. Drain and repeat if necessary.
f. Safety head. Check head to see if it is ruptured; if it is, replace. ([Par 69]) Follow test procedure. ([Par 56 b])
g. Pressure-tank valve. If weapon is to be stored, open pressure-tank valve and leave it open until next charging.
h. Carrier. Scrub, if necessary, with soap and water, or gasoline.
i. Exterior metal surfaces. Scrub exterior metal surfaces clean of fuel to prevent fire hazard. Allow to dry before using again.
j. General inspection. Carefully examine all other parts, adjust as necessary, and replace any which are damaged.
56. SERVICE AFTER SIX FIRING MISSIONS.
After the flame thrower has been used on six firing missions or the equivalent in training work, experienced personnel should follow these directions:
a. Before-operation and after-operation service. Follow the same procedures as in Paragraphs 52, 53, and 55.
b. Test firing (or simulated firing).
(1) If tactical conditions permit test firing at a suitable test range ([Par 15]), fill the fuel tanks with fuel. (Pars [37] through [40])
(2) If test firing with fuel is impracticable, fill fuel tanks with clean water. (Be sure to dry all parts after test.)
(3) Remove filling-plug assembly. ([Par 69]) Fish out the retainer rod and chain by means of a bent wire.
(4) Do not unscrew the safety-head plug.
(5) Insert the testing plug with 0-to 500-pound pressure gage (plug and gage are from service kit) in the filling-plug opening. Tighten testing plug in seat with wrench.
(6) Fully charge pressure tank. ([Par 32])
(7) If test firing with fuel, load ignition cylinder. ([Par 18])
(8) Open pressure-tank valve and simultaneously observe pressure in fuel tanks by reading gage. The gage indicates the pressure in both tanks. It should be between 350 and 390 pounds per square inch.
(9) Read the gage at the expiration of not less than 5 minutes. The tanks should have a pressure reading of not more than 390 pounds. If the pressure continues to increase beyond 390 pounds and the safety head blows, replace the safety head and the pressure regulator.
(10) Fire by operating controls (or simulate firing if tanks are filled with water). The burst should last 3 seconds, during which time the pressure should not drop below 260 pounds.
(11) If the pressure does not conform to the requirements stated in (8), (9), and (10), adjust the pressure regulator upward or downward. ([Par 67 d])
(12) While the above test firing is proceeding, check for leaks at all joints and connections on the tank group. The pressure system should be checked by painting the joints with soap-and-water solution and by looking for bubbles which indicate leaks. For replacement of parts where pressure leaks, see Paragraph 66. Fuel leaks may be seen without soap and water. For repair of fuel leaks, see Paragraph 75 e. The nozzle should be observed by removing the ignition shield. Nozzle leaks are corrected by cleaning, adjusting needle ([Par 75 d]), or by regrinding. ([Par 75 e]) If this is not successful, replace both needle and barrel as a unit.
c. Fuel valve. Discharge all pressure from the gun by operating the fuel valve. Carefully remove the valve grip and grip support. ([Par 74]) Look for signs of leakage at the valve diaphragm. If a leak is present, replace valve-diaphragm assembly. (Pars [75 b] and [75 c])
d. Valve grip. Disassemble the valve grip ([Par 74]) and lubricate. ([Par 49])
e. Carrier. Tighten the carrier cord.
f. Gun interior. If thickened fuel has been fired, disassemble the gun. All parts should be cleaned of accumulations of dried fuel. Lubricate ([Par 49]) and reassemble. If liquid fuel has been fired, flush gun with clean gasoline. Disassemble only enough to lubricate. Reassemble.
Section XV
TROUBLE SHOOTING
57. PRECAUTIONS.
First, remove the ignition cylinder. Then, before disassembling, servicing, or repairing parts which may be under pressure, be sure to release the pressure. Remove fuel, when necessary.
58. FUEL LEAKS.
| Trouble | Remedy |
|---|---|
| a. Defective or damaged valve-diaphragm assembly. | If leak is observed in valve grip, disassemble. ([Par 74]) If diaphragm is torn, or damaged in any other way, remove and replace. ([Par 75]) |
| b. Defective threaded connections on fuel lines. | Disconnect, using wrenches. If thread is stripped or badly damaged, replace the threaded part. If threads appear to be sound, clean them and reconnect. If leak is between tank coupling and tank connector or between hose and fuel-valve body, apply anti-seize compound before rescrewing. Tighten joint with wrenches. |
| c. Dirt or foreign matter on seats or threads. | Clean parts carefully with cloth before reassembling. |
| d. Leak at nozzle. | Adjust needle. ([Par 75 d]) If leak persists, either replace needle and barrel as a unit or use lapping compound on parts. Turn needle in seat until parts make a tight connection when seated. Remove lapping compound and reassemble. |
| e. Worn body of hose. | Replace fuel-hose assembly. ([Par 73]) |
| f. Leak at tank coupling. | Remove and replace coupling washer if damaged. ([Par 70]) If hose nipple, tank end, is damaged, repair nipple ([Par 73 d]) or replace fuel-hose assembly. |
59. SAFETY HEAD “BLOWS” (BREAKS).
| Trouble | Remedy |
|---|---|
| a. Defective safety head. | Replace with new safety head. ([Par 69 b]) |
| b. Defective pressure regulator. | If replacement safety head also breaks, follow test procedure in Paragraph 56 b to determine whether pressure regulator needs adjustment or is defective. |
60. CARRIER UNCOMFORTABLE.
| Trouble | Remedy |
|---|---|
| a. Cord becomes loose or breaks. | Use only hard-braided seine cord furnished in service kit for replacements. Lace tightly as shown in [Figure 46], using slip-proof knots at ends. |
| b. Straps not adjusted to fit wearer. | Adjust straps to fit each new wearer. Tank group must be high on back and snug on body. (Pars [19] and [71]) |
| c. Carrier frame presses on wearer’s back. | Cord is too loose. Tighten cord. Use slip-proof knots at ends. |
61. SHORT RANGE.
| Trouble | Remedy |
|---|---|
| a. Stream of burning fuel issues at an angle or in a very broad spray. | Fuel valve is not fully open because of: (1) Faulty operation. Be sure to compress controls all the way when firing. ([Par 26]) (2) Improper adjustment or assembly of valve. To correct, see Paragraphs [74] and [75]. |
| b. Rapid drop of range during a burst. | Pressure-tank valve is not fully open. Open all the way. If this is not effective, test pressure regulator. ([Par 67 d]) |
| c. Shorter range in each successive burst. | Pressure tank is not fully charged. (1) Before firing be sure tank is charged to at least 1,700 pounds per square inch. ([Par 32]) (2) Check for leaks to make sure pressure has not decreased since charging. ([Par 53 d]) |
| d. Short range with longer time of discharge than 8 to 9 seconds. | Dried fuel or other foreign matter is in fuel lines. Disassemble and clean. |
62. FUEL-VALVE FAILURE.
| Trouble | Remedy |
|---|---|
| Valve fails to close when controls are released. | (1) Work the grip safety to trip the valve lever. (2) Foreign matter may be in barrel, or barrel may be dented. If dented, replace barrel and needle as a unit. If not dented, disassemble and clean. (Pars [74] and [75]) |
63. FAILURE OF IGNITION CYLINDER TO IGNITE.
| Trouble | Remedy |
|---|---|
| a. Match in cylinder moves but incendiary charge does not ignite. | Pull trigger repeatedly. If cylinder does not ignite, remove cylinder ([Par 30]) and examine. (1) If matches have been pushed flush with inner surface of cylinder body, the cylinder is defective. Destroy. ([Par 30]) Replace. (2) If matches project 1/16 inch or more from cylinder, ignition head is defective. Disassemble ignition head ([Par 76 b]) and examine. Replace parts as necessary. ([Par 76] c) |
| b. Cylinder does not rotate to bring new charge into position. | (1) Spring case is not free to rotate because of dirt. Clean and lubricate. ([Par 49]) (2) Cylinder is improperly loaded. ([Par 18]) (3) Ignition cylinder binds on barrel because of dirt or excessive warping of ignition cylinders from heat of firing. Remove and destroy ([Par 30]) ignition cylinder. Reload. (4) Spring case is defective. Replace as a unit. ([Par 76 b], [c]) |
| c. Trigger does not return to normal position (with ignition cylinder in place). | 1) When on a mission, use fingers on trigger to pull back to normal position. (2) If time permits, remove trigger rod. ([Par 76 b]) Clean rod and hole in which rod slides. Lubricate. ([Par 49]) Reassemble. ([Par 76 c]) |
| d. Lack of spring tension at trigger. | Trigger spring is off hook of trigger, off spring screw, or broken. Replace where necessary. |
64. FAILURE OF FUEL TO IGNITE.
| Trouble | Remedy |
|---|---|
| a. Atomizer hole clogged. | Clean with fine wire. ([Par 52 i]) |
| b. Fuel troubles at low temperature. | (1) At temperatures below minus 20 degrees Fahrenheit, ignition of any standard fuel is uncertain. Operation at these temperatures should be avoided unless tests of fuels by firing with flame throwers are first made. (2) At temperatures above minus 20 degrees Fahrenheit, no difficulty should be experienced with thickened gasoline. When blended fuels are used, the ratio of gasoline content should be increased as temperature decreases. |
| c. Failure of ignition cylinder. | See Paragraph [63]. |
Section XVI
TANK GROUP
65. GENERAL.
The tank group stores fuel and pressure. The fuel is placed under pressure when the pressure-tank valve is opened. The tank group is supported upon the firer’s back and shoulders by the carrier.
66. PRESSURE TANK AND VALVE ASSEMBLY.
a. Description and functioning. The pressure tank and valve assembly ([Fig 33]) includes:
(1) Pressure tank. The pressure tank is a lightweight, airplane-type cylinder, able to withstand the great pressure which it contains. The tank is charged with air or nitrogen at 1,700 to 2,100 pounds per square inch pressure by use of auxiliary equipment as described in Paragraphs [31] and [32]. This pressure stays in the pressure tank until the weapon is ready to be fired. Opening of the pressure-tank valve releases air or nitrogen through the pressure regulator to the fuel tanks. Oxygen or combustible gases are never used in the tank because a violent explosion may result. The tank is large in capacity to assure ample pressure, and hence full range, for the entire load of fuel. The pressure-tank clamp ([Fig 39]), a steel-strap device with hinge and toggle-type latch, holds the pressure tank in place on the fuel tanks.
(2) Pressure-tank valve. (Figs [33] and [34]) This valve is screwed into the bottom of the pressure tank. The valve stem slides into the valve end of the valve flexible shaft. When opened by means of the valve handle and valve flexible shaft, the valve permits passage of compressed air or nitrogen through tubes and the pressure regulator to the fuel tanks. The valve is of the quick-opening, packless, diaphragm type.
(3) Pressure-valve handle and valve flexible shaft. (Figs [33] and [34]) The pressure-valve handle is held by a small nut on the end of the valve flexible shaft, which in turn is connected to the pressure-tank valve by means of the valve stem and a large hex nut. The handle and shaft extend to the right of the tank group, enabling the firer to open and close the valve without assistance when carrying the weapon. The handle slips over the end of the shaft and is held to it by a nut. The shaft is held to one of the fuel tanks by a clamp, nut, and bolt welded to the tank.
(4) Check valve. (Figs [33] through [35]) The check valve has the same function as the valve on a vehicular tire tube, but it is much heavier in construction and different in design because the pressure in the flame thrower is 50 times greater than that in an automobile tire tube. Connected by threads to the pressure valve, the check valve permits compressed air or nitrogen to enter the pressure tank during charging (Pars [31] and [32]) but prevents its escape when the outside source of pressure is removed. The cap is removed from the check valve only for charging or testing.
b. Removal. ([Fig 33]) To prevent damage to threads, leaks, and loss of pressure and range, remove pressure tank and valve assembly only when necessary.
Fig 33. Pressure system disassembled, showing nomenclature and Chemical Warfare Service stock numbers for requisitioning spare parts.
(1) Release of pressure. Be sure all pressure has been released from the pressure system before disassembling or removing any part or assembly of the pressure system. To release pressure, operate fuel valve ([Par 26]) and hold open until pressure is exhausted. As an added precaution, personnel should avoid facing the connections when disconnecting parts or assemblies.
(2) Removal procedure. After release of all pressure:
(a) Loosen the clamp from the valve flexible shaft.
(b) Using wrench, unscrew the large hex nut which holds the flexible shaft on the pressure-tank valve.
(c) Pull the valve flexible shaft and handle free of the valve.
(d) Using wrench, unscrew the flared tube nut on the regulator tube adjacent to the pressure-tank valve.
(e) Open pressure-tank clamp ([Fig 39]) and swing clamp strap outward.
(f) Remove the pressure tank together with the pressure-tank valve and check valve.
(g) To remove valve handle, use the adjustable-end wrench to loosen and remove nut from threaded outer end of valve flexible shaft. Slide out the valve handle.
Fig 34. Lower portion of pressure system, assembled.
Fig 35. Check valve (cross section).
c. Installation. (Figs [33] and [39]) To install:
(1) Insert pressure tank (with pressure-tank valve and check valve mounted on the tank) through the pressure-tank clamp. Be sure to aline the regulator tube, elbow, and pressure-tank valve threads carefully so that they cannot be damaged when connecting.
(2) Close the pressure-tank clamp.
(3) Start the threaded connections by hand to be sure they are well alined. Do not force. Use wrench for final tightening, but do not apply great torque to the wrench.
(4) Insert the valve flexible shaft through small clamp into the pressure-tank valve. Using wrench, tighten the large hex nut located between shaft and valve.
(5) Tighten the clamp on the valve flexible shaft.
(6) Place pressure-valve handle on threaded end of the shaft. Place nut on threaded end and tighten with adjustable-end wrench.
d. Adjustment. If valve handle cannot be turned by hand:
(1) Remove flexible shaft and handle. Never apply a wrench to these parts.
(2) Turn end of pressure-valve stem with wrench to open valve.
(3) If stem will not turn, replace the tank and valve.
(4) If stem turns, work it back and forth with wrench.
(5) Reconnect flexible shaft and handle.
(6) If handle does not turn easily, repeat the process until handle turns, or replace tank and valve.
(7) Close valve before charging tank.
e. Maintenance.
(1) If either pressure tank, pressure-tank valve, or check valve are damaged or defective, all three must be replaced as a unit. No attempt may be made to repair any of these parts or their connections. If makeshift repairs or improvised parts are devised, serious accidents can result because of the extremely high pressures to which the equipment is subjected.
(2) Keep all threaded connections tightened. If a leak is suspected at any threaded connection, follow procedure in Paragraph [53 d].
67. PRESSURE REGULATOR.
a. Description and functioning. The regulator automatically reduces the variable pressure of air or nitrogen in the pressure tank to a constant operating pressure of approximately 350 pounds per square inch in the fuel tanks. The regulator is located at a protected position in the tank group of the M2-2 portable flame thrower, where it is not readily subject to tampering or damage from the outside. The regulator tube with fittings connects the pressure-tank valve and pressure regulator. ([Fig 33]) Its outlet is connected to the fuel tanks by the diffusion-pipe assembly. ([Par 68 a]) Either of two interchangeable types of regulators is furnished: the spring type (Figs [33], [36], and [37]), and the dome type ([Fig 38]).
Fig 36. Rear of tank group, with carrier removed to show pressure regulator (spring-type) and connections.
b. Removal of pressure regulator. After release of all pressure:
(1) Remove carrier ([Par 71 b]), if necessary.
(2) Using wrench, unscrew the flared tube nuts and other fittings.
(3) Lift out the pressure regulator.
c. Installation of pressure regulator. Line up pressure regulator, regulator tube, diffusion-pipe assembly, and fittings carefully so they will not be damaged when threads are tightened. Start threads with the hands. Apply only moderate wrench pressure to complete tightening. Replace carrier or carrier pack if either has been removed.
d. Adjustment of pressure regulator. The pressure regulator ordinarily requires no attention other than checking and tightening connections with the regulator tube and the diffusion-pipe assembly. If a defect in the regulator is indicated by falling off of the range of the weapon or by frequent breakage of the safety-head diaphragm ([Par 56 b]), the following procedure should be carried out. (When using wrenches, do not apply excessive force.)
(1) Remove the filling plug ([Par 69 b]) and ignition cylinder. ([Par 30 a])
(2) Fill the fuel tanks with 4 gallons of water (or fuel).
(3) Connect the 0-to 500-pound fuel-tank testing gage, found in the service kit, to the filling-plug hole. Tighten plug of gage with wrench.
(4) Charge the pressure tank to a pressure of 1,800 pounds per square inch. (Pars [32] and [33])
(5) Open the pressure-tank valve.
(6) Read the pressure on the gage. If 350 to 390 pounds is indicated, omit steps (7) through (10).
(7) To increase the pressure of a spring-type regulator:
(a) Pry off the protective cap.
(b) Turn a set-screw wrench clockwise in the adjusting screw and read pressure on gage.
(8) To decrease the pressure of a spring-type regulator:
(a) Turn the set-screw wrench counterclockwise more than is considered sufficient to effect the desired reduction.
(b) Turn the pressure-tank valve off.
(c) Relieve pressure in the fuel tanks by compressing the fuel valve until the pressure is below that desired.
(d) Release the fuel valve.
(e) Open the pressure-tank valve and allow the system to reach a state of equilibrium, which occurs when the hissing sound ceases.
(f) Repeat the steps described above in (6) and (7).
(9) To increase the pressure of a dome-type regulator:
(a) Open needle valve No. 1 one full turn. ([Fig 38])
(b) Open needle valve No. 2 one full turn. (There will be slight leakage around the needle-valve thread.)
(c) Open needle valve No. 3 very slowly, watching pressure gage closely. (As pressure builds up in fuel tanks there will be slight leakage through needle valve No. 1.)
(d) When the pressure gage indicates 350 pounds, close needle valve No. 3 tight.
(e) Close needle valve No. 2 tight.
(f) Close pressure-tank valve.
(g) When gage indicates zero, close needle valve No. 1 tight.
(10) To decrease the pressure of a dome-type regulator:
(a) Open needle valve No. 1 one full turn. ([Fig 38])
(b) Open needle valve No. 3 very slightly, which will lower the pressure.
(c) When 350 pounds is reached, close valve No. 3 tight.
Fig 37. Pressure regulator, spring-type.
Fig 38. Pressure regulator, dome-type, showing needle valves and wrenches.
(d) Close pressure-tank valve.
(e) When gage indicates zero, close needle valve No. 1 tight.
(11) Open pressure-tank valve and press the fuel valve to observe the pressure with the weapon operating.
(12) After final adjustment:
(a) Close the pressure-tank valve.
(b) Open the fuel valve and release the pressure from the fuel tanks.
(c) Remove the pressure gage and plug from the fuel tank.
(d) Install filling plug.
(e) Tighten filling plug with wrench.
(f) If regulator is spring-type, replace its protective cap.
68. FUEL-TANK ASSEMBLY.
a. Description and functioning. (Figs [4], [5], and [39]) The fuel-tank assembly includes:
(1) Fuel tanks. Two alloy steel fuel tanks hold the fuel before it is propelled to the target. They have a combined capacity, including void, of 4-1/2 gallons. A void of approximately 1/2 gallon is left in tanks when filling to allow for expansion and to permit entry of the compressed nitrogen or air. To speed filling and cleaning of the tanks, two openings are provided on top of the fuel tanks. The openings are threaded to receive the filling-plug assembly and the safety-head plug assembly, which are interchangeable in the openings. Filling operations involve the use of auxiliary equipment and are described in Paragraphs [34] through [40]. The carrier and the pressure system are supported on the fuel tanks.
Fig 39. Fuel system of tank group and related parts disassembled, showing nomenclature and Chemical Warfare Service stock numbers for requisitioning spare parts.
(2) Tank connector. This open passageway between the fuel tanks makes them, in effect, a single container. The location of the tank connector and its large diameter permit easy flow of fuel and pressure between the two tanks.
(3) Hose connector. The hose connector is the outlet for fuel from the fuel tanks. It is located so that nearly all the fuel is propelled from the weapon if firing positions are correct. ([Par 24]) One end is welded to an opening in the tank connector. The other end is threaded into the tank coupling.
(4) Frame clamp. This small metal clamp, with bolt, nut, and washer, holds the hose connector to the carrier frame.
(5) Diffusion-pipe assembly. This T-shaped tubing carries compressed air or nitrogen from the pressure regulator to each of the fuel tanks. A flared tube connection and elbow connect the stem of the T to the pressure regulator. The horizontal tubes of the T extend into the fuel tanks and are welded to the fuel tank walls. Within the fuel tanks these tubes are perforated with holes which permit ready escape of the compressed nitrogen or air into the fuel tanks when the pressure-tank valve is open.
b. Removal and installation. The tank connector, hose connector, diffusion-pipe assembly, and the two fuel tanks are welded together and cannot be disassembled from each other. No attempt should be made to remove any of these parts or assemblies.
c. Maintenance. Other than cleaning (Pars [51 d] and [55 e]), repainting, and tightening of threaded joints, no repairs will be attempted by the first or second echelon on the fuel tanks, tank and hose connectors, or diffusion-pipe assembly. Emergency repairs may be made only by the third or fourth echelon. No attempt should be made to weld or patch any part of the fuel tanks.
69. FILLING AND SAFETY-HEAD PLUG ASSEMBLIES.
a. Description and functioning.
(1) Filling-plug assembly. ([Fig 39]) This assembly fits into the 1-3/8-inch threaded opening at the top of either one of the fuel tanks. It permits filling and cleaning of the tanks, and seals the opening when the tank is not being filled or cleaned. The assembly includes the filling plug proper and a plug-retainer assembly. The latter is a metal rod which hangs from the plug on a metal chain. The rod and chain prevent accidental loss of the plug.
(2) Safety-head plug assembly. (Figs [39] and [40]) This assembly is screwed into the threaded opening on top of either fuel tank. It serves the same functions as the filling-plug assembly and moreover protects the firer and other personnel. It includes:
(a) Safety-head plug. This plug is similar to the filling plug except for the threaded hole which receives the safety head.
(b) Safety head. This metal head screws into the safety-head plug. It includes a soft metal diaphragm which bursts when the pressure in the fuel tanks exceeds 500 pounds per square inch. It prevents the building up of dangerous pressures in the fuel tanks.
Fig 40. Safety-head plug assembly (cross section).
Fig 41. Unscrewing safety head from safety-head plug, using wrench.
(c) Deflector tube. This short, curved piece of 1/8-inch pipe deflects fuel and pressure away from the firer if the safety head bursts. A lock nut holds the tube in position. ([Par 12 j])
(d) Plug-retainer assembly. This assembly consists of a metal rod and chain which hang from the plug and prevent accidental loss of the plug when filling or inspecting.
b. Removal of plugs.
(1) Before removing the filling plug, the safety-head plug, or an unbroken safety head, operate the fuel valve until any pressure which may have accumulated in the fuel tanks is eliminated. If the coupling plug is in the tank coupling, very slightly loosen the threads of either the filling plug or the safety-head plug, using the 1-3/4-inch wrench, to eliminate pressure in the fuel tanks. Keep face and eyes away from the threads.
(2) The plug-retainer assemblies should not be lifted completely out of the tanks unless required.
(3) If either the rod or the rod and chain breaks from one of the plugs and falls into the tank, upend the tank group to permit removal of the parts.
(4) To replace burst safety head, unscrew lock nut and deflector tube. ([Fig 11]) Using wrench ([Fig 41]), unscrew safety head. Never disassemble the safety head.
c. Installation of plugs. The filling plug, safety-head plug, and safety head are screwed in by hand and then tightened with wrenches. No substitution will be made for the safety head, which is manufactured to burst at the safe limit of pressure. The plug threads and seats should be cleaned with a cloth ([Fig 29]) before installing plugs. Screw in deflector tube, using hand pressure. The tube outlet should face to the rear and at a 45-degree angle to operator’s left shoulder. ([Fig 18]) Replace lock nut and tighten with wrench. (Use wrench on lock nut, not on deflector tube.)
d. Maintenance of plugs. Replace safety head if damaged or blown. Never repair safety head or use an improvised head.
70. TANK COUPLING.
a. Description and functioning. This quick-connecting coupling ([Fig 42]) connects and locks the fuel hose or the coupling plug to the tank group. The coupling cams, lock, and washer provide a secure and tight joint. The tank coupling makes possible rapid replacement of emptied tank groups with filled and charged tank groups in the field. No tools are needed for this operation.
Fig 42. Tank coupling and end of fuel-hose assembly.
b. Removal.
(1) To remove the tank coupling from the hose connector, apply a wrench and unscrew.
Fig 43. Closing cams of tank coupling to connect gun and tank group. This is done before locking. (See below.)
Fig 44. Closing lock of tank coupling to secure gun to tank group. This also provides a fuel-tight seal.
(2) To disconnect the tank coupling from the fuel hose or the coupling plug:
(a) Release pressure from fuel tanks by operating the fuel valve or by opening very slightly the filling plug.
(b) Using hands, pivot the coupling lock back on the coupling body.
(c) Using hands, pivot the two coupling cams back on the coupling.
(d) Slide out the fuel hose or the tank coupling.
(e) If coupling washer is to be removed, pry out with a screw driver.
c. Installation of tank coupling. Proceed as follows:
(1) If coupling washer has been removed, replace.
(2) Insert coupling plug or hose nipple, tank end, in the coupling as far as it will reach. Close the two cams. ([Fig 43])
Fig 45. Coupling plug in place in tank coupling. This arrangement is used when fuel tanks are brought back for filling with gun detached.
(3) Close the coupling lock ([Fig 44]), being sure to push it all the way, until it covers the ends of both cams. ([Figure 45] shows coupling lock correctly locked on coupling plug.)
(4) If the tank coupling has been removed from the hose connector, screw it on hand tight. Anti-seize compound should be applied lightly to the threads to assure a tight joint. Use wrench to tighten the coupling until it is in the position shown in [Figure 34].
d. Maintenance of tank coupling. The coupling washer, made of synthetic rubber, should be inspected frequently. If it is damaged or swollen, remove it and replace. If the coupling leaks, inspect, and if necessary, remove and replace the washer.
71. CARRIER.
a. Description and functioning. ([Fig 46]) The tank group is securely carried on the firer’s back and chest by the carrier, which includes the metal carrier frame, the canvas carrier pack, webbing straps, and cord, all of which are parts of the tank group.
(1) Carrier frame. This lightweight, tubular-metal frame is bolted to two pairs of brackets (upper and lower) on the fuel tanks. It is also bolted to the hose connector by the frame clamp, which helps support the connector. The frame is pierced by two parallel series of holes, through which the cord (lashing) of the carrier is laced.
(2) Carrier pack. This is a sheet of heavy canvas, reinforced on the tank side with strips of webbing. The smooth side of the carrier pack rests against the firer’s back and cushions the back from contact with the metal tanks. A series of eyelets is located on each side of the pack.
(3) Seine cord (lashing). The carrier pack is fastened to the carrier frame by means of hard-braided cord which is laced through the eyelets in the pack and the holes in the frame. The cord that comes on the flame thrower stretches very little under load.
(4) Straps. The straps, made of wide cotton webbing, are adjustable to fit the wearer. ([Fig 18]) They are provided with snap release, hook-and-eye, and snap fasteners. The shoulder straps have quick-release fasteners for rapid removal, if necessary, of the tank group from the firer. The upper ends (steel loops) of the shoulder straps are secured by pins to the steel support which connects the two fuel tanks. Each of the pins is held in position by a split cotter pin, which is inserted through a hole in the pin and is then spread. The lower ends of the shoulder straps snap onto metal loops at the bottom of the carrier frame. The upper body straps are attached to metal loops on each side of the carrier frame. The lower body straps are fastened to one of the lower two pairs of eyelets of the carrier pack.
b. Removal of carrier.
(1) To remove carrier or carrier frame, use screw driver and adjustable-end wrench to take off frame clamp, bolt, nut, and lock washer. ([Fig 34)] Then remove two pairs of bolts, nuts, and lock washers which hold the carrier frame to bottom and top of the fuel tanks. Lift off the carrier.
(2) To remove body straps, unsnap ends and lift out of holes. To remove shoulder straps, unsnap lower ends and remove from holes. Pull out cotter pins, then pins, from upper ends of shoulder straps, and lift out straps.
(3) To remove carrier pack, unknot and unlace cord.
c. Installation of carrier.
(1) To install carrier frame (or a complete carrier) place frame in position adjacent to fuel tanks ([Fig 46]), insert bolts in holes, place lock washers and nuts on bolts, and tighten with screw driver and wrench. Replace frame clamp on fuel connector and frame. Insert bolt in holes, place lock washer and nut on bolt. Tighten with screw driver and wrench.
(2) If carrier pack has been removed, use cord to relash. Lace tight and use slip-proof knots. ([Fig 46])
(3) To install straps, snap ends of body straps and lower ends of shoulder straps into positions shown in [Figure 46]. Place upper ends (steel loops) of shoulder straps in steel support between fuel tanks. Insert two pins through any two of the holes in the support and through the shoulder strap loops. Insert cotter pins in holes in pins and spread cotter pins to lock pins in place.
d. Adjustment of carrier. Carrier must be carefully adjusted to fit the individual firer so the load will not shift during sudden, rapid changes of firer’s position. Adjustments are as follows:
(1) Cord and carrier pack. Cord must be tight at all times. The cord furnished with the equipment has very little tendency to stretch. However, pull cord tight when lacing and use slip-proof knots at ends. Tighten cord periodically.
Fig 46. Carrier assembled on tank group.
(2) Straps. Adjust straps to fit each firer, moving slides on straps as necessary. Straps must fit snugly to prevent shifting of load and to keep tank group high on firer’s back. Lower body straps may be fastened in second pair from the bottom of carrier eyelets to conform to firer’s physique. Pins, which hold top ends of shoulder straps to steel support between the fuel tanks, may be moved to any two of the three holes so as to provide the best balance in the load.
e. Maintenance of carrier. Keep carrier dry and clean. If flame thrower becomes wet or muddy, clean and dry carrier thoroughly. Store in a dry place. If rotted, mildewed, or damaged, replace affected parts. If cord frays or breaks, use special seine cord from service kit as replacement.