AirPrime™ Information

World Class

Fire Industry




A Trident Model #31.013.42 automatic air operated multiple priming system shall be installed. The unit shall be of all brass and stainless steel construction and designed for large capacity fire pumps of over 3,000 GPM (11,350 LPM). Due to corrosion exposure, no aluminum or vanes shall be used in the primer design. This unit shall consist of three (3) primers operated by a single panel mounted control. Each primer shall be of a two-barrel design with ¾” NPT connections to the fire pump.


The primers shall be mounted above the pump impeller so that the priming line will automatically drain back to the pump. The primers shall also automatically drain when the panel control actuator is not in operation. The inlet side of the primers shall include brass ‘wye’ type strainers with removable stainless steel fine mesh screens to prevent entry of debris into the primer bodies.


Performance, Safety, and NFPA Compliance


The priming system shall be capable to a vertical lift to 22 inches of mercury and shall be fully compliant to applicable NFPA standards for vertical lift. The system shall create vacuum by using air from the chassis air brake system through a two-barrel multi-stage internal “venturi nozzles” within the primer body. The noise level during operation of the primer shall not exceed 75 Db.


Air Flow Requirements


The primer shall require a minimum of 30 cubic foot per minute air compressor and shall be capable of meeting drafting requirements at high idle engine speed. The air supply shall be from a chassis supplied ‘protected’ air storage tank with a pressure protection valve. The air supply line shall have a pressure protection valve set between 70 to 80 PSIG (4.8 to 5.5 BARG).


Automatic Primer Control and Vacuum Gauge Panel


The 12 volt primer control shall be an “automatic” type, with a pump panel three-way switch to operate an air solenoid valve. The air valve shall direct air pressure from the air brake system to the primer. To prevent freezing, no water shall enter the primer valve control.


A 2” diameter vacuum gauge, with graduations from zero (0) to 30 feet, shall be installed in the panel mounted primer control. The gauge shall be physically connected to the vacuum side of one of the primers and read only when the priming system is running. The gauge shall never see or be subjected to damage from high pump intake pressures.


The automatic priming switch shall have three positions as follows:


  • “Prime” – The lower position shall be a momentary “push to prime”. The “Prime” position also allows the operator to “ramp” test the primer without the fire pump being engaged.
  • “Off” – Center position.
  • “Auto-Prime” – In the upper position, a “green” LED pilot light shall be illuminated when the switch is the auto-prime position. The “Auto-Prime” operates automatically when the pump pressure drops below 20 PSIG.   The primer shuts “off” automatically when the pump pressure is re-established and exceeds 20 PSIG.    The “Auto” mode only operates when the fire pump is engaged.


Power Requirements


To reduce the electrical power requirements on the fire apparatus the priming system shall be air powered. The system shall not require annual tear-down and maintenance, an electric motor, lubrication, belt drive, or clutch assembly. The maximum current draw shall not exceed 0.5 amps during operation.




The primer shall be covered by a five (5) year parts warranty.


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