Carbon Dioxide Low-Pressure Systems

Check nozzles, pressure and level gauges, and for leaks in all devices.

Weekly, check to see that all nozzles are clear and in the proper position and that all operating controls are properly set. Check and record the reading on the liquid level gauge of all storage tanks. Refill tanks when the quantity is less than the minimum required to protect the largest single hazard, including any required reserve supply.

Monthly, check for leaks on all devices and connections under continuous pressure, including valve packing glands, screwed connections, and safety relief valves.

Semiannually, test the tank-alarm pressure switch and the operation of the alarm bell or light by reducing and increasing the pressure. Perform this test as follows:

. Close valve on the piping from the vapor space to the alarm pressure switch.

. Remove the test plug to reduce pressure. l Increase pressure by connecting a highpressure cylinder to the test opening.

. After testing, disconnect the high-pressure cylinder, replace the test plug, and reopen the valve on the alarm pressure switch piping. 

l If the bell or light fails to operate on the pressure test, repair or replace, and test again.

Check the liquid level and pressure gauges for accuracy once each year.

Replace frangible disks on the storage tanks once every 5 years. Maintain refrigeration equipment according to the manufacturer's instructions.

Halogenated Systems

Follow these procedures to test halogenated systems. Weekly: check to see that all nozzles are clear, positioned properly, and all operating controls are set properly. Semiannually: check weight and pressure containers. (See procedures for verifying CO2 cylinders.) If the container has a loss in net weight of more than 5 percent or a loss in pressure (after adjusting for temperature) of more

than 10 percent, you must either refill or replace the container. When a factory-charged nonrefillable container does not have a pressure indicator that shows a loss in net weight of more than 5 percent, you must replace the container. Annually: test all actuating and operating devices. Use a cylinder containing carbon dioxide in the place of a halon cylinder or perform a simulated test of pressure-operated devices.

Alarm Systems

You should perform tests and maintenance of detectors, circuits, control units, annunciators, relays, and power supplies, as described in Maintenance of Fire Protection Systems, NAVFAC MO-117, chapter 3,. Some additional steps are required to test cross-zoned detectors, electrically operated releases for gaseous agents, and an abort feature.

Release Devices and Auxiliary Functions

Test electrically operated release devices for gaseous extinguishing systems annually. Combine this test with tests of detectors and the total alarm system. If you cannot perform an actual discharge test, be sure to prevent gas discharge and computer power shutdown, if provided, while observing electrical functions. This may require valve closure or partial disassembly of diaphragm piercing, solenoid plunger-type valves, and manual override of the computer shutdown feature. Refer to system instructions from the equipment manufacturer or installing company. The same method, once determined, is normally used for testing manual devices connected electrically to cause direct actuation of gas release devices. After taking necessary steps to prevent gaseous discharge, you should cause the necessary alarm conditions to activate the extinguishing system by actuating the detectors or manual initiating devices. At the end of the time delay intend, release device actuation should be evident. Verify that relays for auxiliary functions actuate. Take notes on which event relays actuate at the first cross-zoned detector alarm, second cross-zoned detector alarm, and at the end of the timer intend. Note the amount of time delay between the second detector actuation and the delayed functions.

If release devices or auxiliary functions fail,

you should replace the control unit in the alarm condition and check appropriate output voltages at the control unit and at the failed device. If voltages are improper, troubleshoot the control unit or circuit as indicated. Cross-zoned systems require an alarm condition on both initiating circuits to actuate release devices and some auxiliary functions. If a timed fiction fails, check input voltage to the timer and the delayed output voltage from the timer with a voltmeter. Replace the timer if input is proper but output is not. If voltages are proper, check solenoid and relay coil continuities with one side of their respective energizing circuits open to the control unit. (See testing and maintenance for foam systems,

Maintenance of Fire Protection systems, NAVFAC MO-117, section 7.3.1.) Replace defective devices and/or wiring.

Abort Feature

In gaseous extinguishing systems with an abort feature, test the feature annually along with the other elements of the system. To test the abort feature, first determine the timer setting from prior test records or installation data. Then cause first and second cross-zoned detect or alarms. The second detector alarm starts the timed period during which the gaseous agent release and other abortable functions may be activated. Operate the abort switch approximately in the middle of the time interval. Perform this test with the agent release and computer shutdown features disabled. At the end of the time interval, confirm that the aborted functions do not occur. Possible causes of abort failure are as follows:

l a defective abort switch,

. a defect in the wiring between the abort switch and the main control unit, or

. an improper abort feature installation or an improper timer setting (low).

During troubleshooting, disable the extinguishing agent release and the computer shutdown feature, if provided. Check the abort timer setting according to the manufacturer's instructions. If the timer setting is quite low, 15 seconds or less, increase the setting to 20 seconds or more (as determined by local authorities to be adequate to prevent unnecessary discharge of the agent).

If actuating the abort switch has no effect, check the switch continuity with an ohmmeter while actuating it disconnected from its wiring. If the switch continuity shows alternating readings of zero ohms and infinite resistance, as it should when being repeatedly actuated, check that the OFF and ON positions of the switch are not reversed. (Such reversal may be caused by connecting the wires to the wrong pair of switch terminals or inverting the switch when mounting it.) If the switch has no defect, check its circuit continuity with an ohmmeter at the control unit and with at least one wire disconnected from the control unit. Observe switch action at the ohmmeter by actuating the switch repeatedly. Correct any circuit defects or wiring errors. Replace the switch if it is defective.

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