BREATHING

The air compressor shall be a turnkey, packaged appliance designed to deliver high pressure breathing air in compliance with the most current NFPA and CGA quality standards.  The unit shall include the high pressure air compressor, electric motor, air purifier and all operating controls as specified below and be completely assembled and tested by the manufacturer requiring only electrical power supply to operate.  The unit shall be designed so that all operating controls and performance indicators are located on a panel at the front of the appliance allowing “at sight” operator monitoring.  The appliance shall comply with the currently applicable OSHA specifications as well as state and local electrical codes.  The compressor design shall not permit the venting of oil contaminated air to the atmosphere.

The external construction of the high pressure breathing air compressor shall be appliance-like; using formed fabricated steel structures and panels without visible welds, burrs or grinding marks.  All structure fasteners shall be concealed and all access panels shall include concealed hinges and push button latches.  One, full height door shall be provided on the appliance for maintenance access.  The door shall include a shutdown switch to prevent exposure to running gear in the event that it is opened while the compressor is running. 

The cabinet configuration shall permit installation with the rear “against the wall” and include an ambient air flow control design that directs the necessary volume to cool the compressor.  The cooling system shall also include an integral top discharge extractor to completely vent the resulting hot air out of the cabinet.

All high pressure air plumbing shall be rated for 6000 PSI working pressure and utilize seamless stainless steel tubing.  All high pressure air plumbing connections shall use compression fit design fittings.

The ambient air filter element shall be located in a housing installed directly on the compressor inlet with an opening suitable for outside air intake piping.

The electrical control system shall include components with UL, NEMA or IEC approval and housed within a NEMA 1 enclosure.

II.  Compressor

The ambient air intake and compression shall be through an air-cooled, reciprocating, three-stage compressor designed for continuous duty at 5000 PSI working pressure with a charging rate of 8.0 CFM.  The air compressor design shall include a heavy-duty crankcase supporting the crankshaft with ball bearings on each end.  Lubrication shall be accomplished by controlled splash of oil from the crankcase sump aided by pressure induced migration from the totally sealed crankcase.

The crankcase shall be piped back to the inlet cylinder to maintain proper crankcase pressure and eliminate any discharge of oil contaminated air to the atmosphere.  The cylinder arrangement shall be a balanced “V” configuration featuring double-acting, ringed pistons assuring maximum balance and air volume delivery efficiency while operating at a maximum compressor speed of 1700 RPM.  Each stage of compression shall be protected with a safety relief valve.  The cylinders shall include cooling fins to dissipate heat into the cooling air flow from the compressor’s integral flywheel fan.  Individually mounted coolers shall be located after each compression stage to cool the discharged air to 18° F. above ambient temperature.  Accumulated condensation from cooling the compressed air shall be collected in moisture separators mounted on the compressor and piped to an automatic, timed drain system for proper collection and disposal.  Prior to shutdowns, the compressor shall be allowed to run unloaded (with opened drains) for a timed period (Purge Cycle) in order to purge all cylinders, separators and crankcase of damaging condensation that develops as compressors cool down.  

III.  Electric Motor

The compressor shall be v-belt driven by a NEMA design 7.5 HP, open drip proof electric motor wired for  the electrical conditions as shown below:

The motor shall be located under the compressor and driven via v-belt drive arrangement utilizing a hinged motor base to facilitate belt tension adjustment.  The compressor and motor base shall include zinc plated, steel encased neoprene mounts to isolate vibration from the appliance.

IV.  Electrical Control System

The breathing air compressor shall include all the necessary controls to assure efficient and safe operation and monitor performance. The control system shall be of an anti-flutter circuit design and include a latched fault protection circuit to prevent automatic restarting after an abnormal fault has occurred. As a minimum, the control system must include the following:

• Air pressure switch to automatically start and stop the compressor based on demand.
• High air temperature shutdown switch and gauge with thermowell and sensor that measures temperature directly from the air stream.  Cylinder surface sensors are not acceptable.
• Low oil level shutdown switch.
• Magnetic, across-the-line starter with electric motor overload protection.
• Dual air pressure switch with a panel-mounted selector for automatic start and stop control at two pressure settings.  (A)
• Compressed air electronic carbon monoxide (CO) detector with pre-set warning and shutdown limits.  (B)
• Compressed air electronic moisture (H2O) detector with pre-set warning and shutdown limits.  (C)
• AirMonitor including CO and H2O detectors with pre-set warning and shutdown limits.  (D)

V.  Instrumentation

The control system must include clearly labeled monitoring devices to indicate normal and fault shutdown operating conditions. These shall be mounted on a steel control panel located at the front of the appliance.   The panel shall be painted in a matte shade with a textured finish to eliminate glare and enhance the visibility of gauges and indicators.

The compressor’s instrumentation panel shall be engineered for quick and convenient access to all key panel components, eliminating the need to use the appliance maintenance access door.  Pressure gauges, indicator lights, the start/stop control pressure switch and all optional instruments shall be accessible for routine maintenance and adjustments from hinged, “knockdown” sub-panels located within the main control panel surface.

The compressor shall also include a condensate purge test switch in order to verify proper operation of the automatic condensate drain system on demand.

As a minimum, the instrumentation required is as follows:

• Compressor interstage and final pressure gauges.
• Hourmeter.
• Compressor final stage temperature gauge.
• Illuminated power selector (on/off) switch.
• Normal high air pressure shutdown indicator light.
• Purge cycle indicator light and test switch.
• General fault shutdown indicator light.
• Emergency stop button.
• Inlet filter restriction indicator, mounted on compressor's 1st stage intake.
• High/Low air pressure selector switch.  (A)
• Digital CO monitor panel with actual content display in parts per million (PPM) and prompter software keypad for calibration.  A flow panel with factory plumbed calibration gases shall be included.  (B)
• Digital H2O monitor panel with actual content display in PPM.  (C)
• Digital CO and H2O panel with actual content display in PPM and prompter software keypad for CO monitor calibration.  A flow panel with factory plumbed calibration gases shall be included.  (D)

VI.  Air Purification System

The high pressure air purification system shall be a multi-chamber arrangement that utilizes disposable cartridges manufactured to provide breathing air that meets or exceeds NFPA and CGA Grade “E” specifications and all other equivalent and recognized standards in use worldwide.

All system components shall be rated for 6000 PSI working pressure.  All chambers in the system shall be constructed of 304 stainless steel to enhance safety and corrosion resistance.

The purification system shall be sized to process 15,000 cubic feet of air at 80° F. and compressed to 6000 PSI between cartridge changes.

The purification system shall be sized to process 35,000 cubic feet of air at 80° F. and compressed to 6000 PSI between cartridge changes.

 The system shall include the following:

• Final separator chamber connected to the automatic condensate drain system.
• Check valve to prevent back pressure to the compressor.
• One (1) purifier cartridge chamber.
• Pressure maintaining valve to assure that the system is maintained pressurized in order to attain the rated processing capacity of the air purification cartridges.
• Adjustable start/stop control pressure switch.
• Safety relief valve.
• Panel mounted manual isolation valve and purifier mounted drain valve to relieve the system pressure for maintenance.
• Stem-mounted gauge for system pressure verification.
• Visual CO/H2O indicator.

The system shall be designed so that filling cannot occur in the event that the disposable cartridge is not installed.