Usage:
988B ( 50W6041-up);
992C ( 49Z1-931);
834B ( 92Z1-up);
D8L ( 53Y1-3484);
D9L ( 14Y1-3133);
D10 ( 84W1-up)
Introduction
This instruction gives the procedure for repairing, servicing and charging the 7T9995 Nitrogen Actuator. This actuator replaces both 5G3015 and 5G2960 Actuators.
Reference: Service Manual, Parts Book.
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The nitrogen actuator cylinders in Caterpillar Fire Suppression Systems require periodic inspections and maintenance to meet requirements set forth by the National Fire Protection Association. Discharged nitrogen actuator cylinders require a thorough visual inspection and a hydrostatic test for strength before recharging, if more than five years have elapsed since the last hydrostatic test. Fire equipment distributors can do the hydrostatic tests. They must also be given a visual inspection and hydrostatic test if the agent cylinder has sustained structural damage or shows signs of corrosion prior to the five year time frame. Nitrogen actuator cylinders that have not been discharged, may be left in service for twenty years from the date of the last inspection and test. After twenty years in service, these cylinders must be depressurized, emptied, visually inspected, hydrostatic tested and marked (dated) before being returned to service. After hydrostatic testing, it is very important that the nitrogen actuator cylinder be thoroughly dried before recharging. |
Charging Procedure
7T9995 Nitrogen Actuator
1. When an uncharged nitrogen actuator is received for charging, check the unit for damage. If 6T6098 Cartridge (1) is damaged by dents or deep scratches, it should be replaced.
2. Check 7W7088 Pressure Indicator (2), 5G3126 Gauge Guard (3) and 7T8775 Lock Pin (4) for damage. Any damaged or missing parts must be replaced before charging the actuator.
(12) Parts from 7S5437 Nitrogen Charging Group. (13) 8S4600 Nipple. (14) 7W7088 Pressure Indicator. (15) 1S8937 Valve. (16) 5P8998 Nipple. (17) 2D7325 Tee. (18) 6V4144 Coupler. (19) 3D8927 Hose Assembly.
3. Remove the 1S8941 Hose Assembly from the charging group and replace it with the parts shown above.
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High pressure nitrogen is present. Injury to personnel is possible. Make sure the lock pin is installed in the cylinder. |
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5. If the gauge indicates pressure the cylinder may still have pressure or the gauge may be defective. If flag seal (5) is broken or if lock pin (4) is missing, the cylinder is probably empty.
6. Carefully remove plug (6), knob (7) and plunger (8) as a unit from 7T9964 Valve Body (9). Check parts for defects. Replace defective parts with new parts.
7. Check in the bore of the valve body and observe 3T9384 Burst Disc Plug Assembly (10) at the bottom of the bore.
- * If the disc is ruptured, the cylinder is empty. If the gauge shows pressure, the gauge is defective and must be replaced. Tighten the new gauge to 13 ± 2 N·m (9.6 ± 2 lb ft).* If the disc is not ruptured, the actuator may still have pressure.
6V7906 Plug Wrench
8. If the actuator has no pressure, install 6V7906 Plug Wrench (22) into the valve body bore, engaging the wrench to 3T9384 Burst Disc Plug Assembly (10).
9. Remove the burst disc plug assembly by turning the wrench counterclockwise.
10. Carefully clean the threads to be sure that there are no burrs left after removal of the plug assembly. This is to prevent these particles being expelled from the cylinder during discharging of the actuator.
11. Add 5 mL (1 tsp) of Halon 2402 into the valve body to provide leak detection tracer. Do not spill any Halon 2402 on the plug assembly threads.
NOTE: Remember to always add 5 mL (1 tsp) of Halon 2402 whenever the actuator is discharged.
12. Install a new 3T9384 Burst Disc Plug Assembly (10) into the actuator valve body using 6V7906 Plug Wrench (22).
13. Tighten the plug assembly finger tight, then back off one to one and one half turns, leaving the plug wrench in place.
14. Remove 127950 Plug (11) from the outlet port of the valve body.
15. Install 6V3965 Nipple Assembly (21) in the outlet port.
(23) Gauge. (24) Input. (25) Gauge. (26) Screw. (27) Valve. (28) Valve. (29) Coupler.
16. Close valves (27) and (28).
17. Connect hose end with coupler (29) to 6V3965 Nipple Assembly (21).
18. Connect regulator input (24) to a source of dry nitrogen.
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Dry nitrogen is the only gas approved for use in the actuator cylinder. Charging the actuator cylinder with oxygen gas may cause an explosion. This hazard will not happen if nitrogen cylinders with standard CGA (Compressed Gas Association, Inc.) Number 580 connections are used. When you order nitrogen gas, be sure that the cylinders are equipped with CGA No. 580 Connections. Do not use color codes or different methods of identification to tell the difference between nitrogen and oxygen cylinders. |
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19. Adjust screw (26) until gauge (23) reads approximately 4133 kPa (599 psi).
NOTE: Gas pressure is variable with temperature. The cylinder must be at the same temperature as the air around it before it can be charged. Use the following chart for the correct nitrogen charging pressure.
20. Open valve (27) and charge the cylinder to 4133 + 140 - 0 kPa (599 + 20 - 0 psi) at 21°C (70°F) while gauge (25) is read.
21. Close valve (27) and check gauge (25) for the correct pressure. If not correct, make an adjustment to screw (26) and open valve (27).
22. Use a torque wrench on the hex end of 6V7906 Plug Wrench (22) and tighten 3T9384 Burst Disc Plug Assembly (10) to a torque of 34 ± 4 N·m (25 ± 3 lb ft).
23. Remove plug wrench (22) and close valve (27).
24. Check gauge (2) to verify that the gauge needle is in the green area. If the gauge needle is not in the green area, recheck cylinder pressure and replace gauge if it is in error.
25. With valve (27) closed, slowly open valve (28) to release the fill hose pressure.
26. Disconnect coupler (29) and nipple assembly (15) from the actuator outlet port.
27. Reinstall 127950 Plug (11) with 9S3263 Thread Lock and tighten to 13 ± 2 N·m (10 ± 1 lb ft).
NOTE: Refer to section titled Testing and Repair Procedure to check for leaks before actuator is completely assembled.
28. Be sure the flag seal (5) and lock pin (4) are in place before installing the plunger assembly in the valve body.
29. Apply a small amount of 5N5561 Silicone Lubricant to the o-ring seal of plug (6) and to plunger (8).
30. Install plunger assembly in the valve body and tighten to a torque of 68 ± 10 N·m (50 ± 7 lb ft).
31. Install actuator on vehicle.
NOTE: When installing actuator on vehicle, orient lock pin so that it may be easily removed.
32. Replace 6T0005 Flag Seal (5) on actuator when lock pin orientation is changed.
Testing and Repair Procedure
1. Check for nitrogen and Halon 2402 leaks using a 6V4135 Leak Detector.
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When using pressure air wear a protective face shield and protective clothing. The maximum air pressure at the nozzle must be below 205 kPa (30 psi) for cleaning purposes. |
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2. Use pressure air to remove (blow) any Halon 2402 that might be spilled from the area around the burst disc plug assembly before checking for leaks. This prevents false indications from the detector.
3. If leaks are found, determine the leak point. Disassemble the actuator as necessary to correct the leak.
4. 9S3263 Thread Lock may be used on the threads of the gauge, valve body or outlet port plug to seal a leak in any of these areas.
5. Assemble the actuator after any repair.
6. Recharge the actuator with nitrogen and check again for leaks.