The RIX Compressor Family: 2V3B-4.1V is a 3-stage, 3-cylinder, air-cooled, oil-free oxygen compressor designed for the compression of dry oxygen. This manual provides comprehensive instructions for its installation, operation, and maintenance.
Function Description
The compressor operates by successively compressing gas through three stages. After each stage, the gas is cooled in a heat exchanger by ambient air, which is then routed towards the compression cylinders. The compression cylinders are isolated from the crankcase lubricating oil by crosshead distance pieces and metal slingers on the piston rods, ensuring oil-free compression. Teflon-based piston rings are used in all stages. The entire crankcase assembly, including guide cylinders, is splash lubricated with automotive-type oil.
Important Technical Specifications
The compressor is designed for specific operating conditions to ensure safety and optimal performance.
Gas Input:
- Design Gas: Clean Dry Oxygen
- Pressure: 30 to 40 PSIG
- Dew Point: -40 °F Maximum
Gas Output:
- Flow: 10.6 SCFM* at 40 PSIG, 100 °F inlet (*Design basis of SCFM is 70°F and 14.7 psia)
- Pressure: 2500 PSIG Maximum
General Design:
- Design Speed: 540 RPM
- Compressor Design: Three stage, oil-free compression, air-cooled
- Cylinder Sizes: 2 1/4" & 1 3/8" & 5/8"
- Stroke Length: 3"
Electrical Requirements:
- Drive Motor: 10 HP
- Control Circuit Voltage: 230 VAC
- Supply Power (P1A): 208-230VAC/3PH/60HZ
- Supply Power (P1B): 460VAC/3PH/60HZ
- Supply Power (P1C): 380-415VAC/3PH/50HZ
- Supply Power (P1E): 380-415VAC/3PH/60HZ
Operating Environment:
- Installation: Indoors or Weather Protected
- Ambient Temperature: 35 to 104 °F
- Altitude: Sea Level to 4500'
Normal Operating Pressure Ranges:
- Suction: 30-40 psig
- 1st Stage: 190-250 psig
- 2nd Stage: 700-820 psig
- 3rd Stage: up to 2500 psig
- Back Pressure Regulator setting: 1500 psig (approximate)
Relief Valve Settings:
- Suction (RVI): 50 Psig
- 1st Stage (RV1): 300 Psig
- 2nd Stage (RV2): 1000 Psig
- 3rd Stage (RV3): 2800 Psig
Safety Switch Settings:
- Discharge Gas Pressure (SPD): Stop at 2500 psig max, Start at approx 500 psi less
- Suction Gas Pressure (SPI): Stop at 30 psig falling, Start at 40 psig rising
- High Gas Temperature: Shutdown at 400 °F Max* (*Temp switch to be set 30°F above maximum observed operating temperature or 400 °F, whichever is lower.)
Usage Features
The compressor features a control system with two modes of operation:
- Manual Start / Automatic Stop: The unit starts manually and stops automatically based on safety switches.
- Auto Start / Stop: The unit automatically starts and stops based on both suction and discharge pressure.
An HOA (HAND/OFF/AUTO) switch on the control panel allows selection between these modes. The suction and discharge pressure switches have adjustable "cut in" (start) and "cut out" (stop) settings. An E-Stop button is provided for emergencies, disconnecting all power to the control box. In AUTO mode, pulling the E-Stop button will cause the unit to automatically restart once the button is reengaged, so it is recommended to place the HOA switch in OFF mode before pulling the E-Stop button.
02 Burn-in Procedure: This critical procedure must be followed at initial start-up and anytime the compressor or associated plumbing has been disassembled and exposed to the atmosphere. It involves pressurizing the system with clean, dry nitrogen (or a nitrogen/oxygen mixture not exceeding 30% oxygen), running the compressor under specified conditions, and slowly injecting oxygen into the inlet while venting the discharge for at least 30 minutes to safely oxidize any organic materials.
Maintenance Features
Routine Inspection:
- Check crankcase oil level (3/4 up the sight glass) and for oil leaks.
- Verify gauge pressures against normal operating cylinder pressures.
- Check cooling air flow and ensure heat exchanger fins are clean.
- Listen for unusual noises or vibrations.
Scheduled Maintenance:
- Filter Cleaning: Every 3000 hours or as required.
- Crankcase Lubricating Oil: Change every 3000 hours or annually. The unit is shipped dry, so oil must be added before the first run. Automotive type oil (synthetic or carbon-based) is recommended; multi-viscosity oil is acceptable, but synthetic compression oils are not.
- Viscosity: SAE 30W (Above 60°F), SAE 20W (Between 32° and 60°F), SAE 10W synthetic preferred (Between 20° and 32°F), synthetic oil required (Below 20°F).
- Drive-belt Adjustment: Annually. New belts may require tightening after 24-48 hours.
- Electric Motor Lubrication: As required (follow manufacturer's recommendation if grease fittings are present; otherwise, bearings are sealed for life).
- Pressure Relief Valves: Inspect, clean, and test for correct set-point every 8000 hours or annually.
- Gas Piping Leak Check: Every 1000 hours or after maintenance. Use a soapy water solution to detect leaks.
- Compressor Valves: Inspect every 4000 hours or earlier if pressures vary, flow drops, or noise/high temperature is observed.
- Piston Rings (3rd stage): 1500 hours or as required.
- Piston Rings (2nd stage): 3000 hours or as required.
- Piston Rings (1st stage): 4500 hours or as required.
- Cylinder Liners: As required.
- Piston Rod Oil Seals: As required.
Corrective Maintenance:
- Alignment of Drive Pulleys: Necessary after removing the motor sheave or compressor flywheel. Pulleys are keyed to the shaft and locked with a tapered bushing. Alignment is achieved by sliding the pulley and hub on the shaft, ensuring the gap between the straight edge and flywheel/pulley does not exceed 1/16" (4 CM).
- Tightening V-Belts: Proper tension allows one-quarter inch deflection with 8-10 lb. force at mid-span.
- Cylinder Heads: Fasteners must be removed and installed in an alternating pattern, avoiding overtightening.
- Compressor Valves: Inspection for wear, cracking, warping of reeds, and damage to valve seats. Lapping or polishing valve seats may be required.
- Piston Rings: Replacement is necessary as they wear, indicated by diminished sealing ability, lower compressor capacity, or increased inter-stage pressures. The 3rd stage floating piston should be replaced as an assembly at the first change-out.
- Cylinder Liners: Checked for surface finish, scoring, or excessive wear if ring life deteriorates. Re-honing may be required to achieve a 16-32 crosshatch surface.
- Piston Rod Oil Seals: Replaced if crankcase oil leaks into the distance piece area.
- Piston Rod Adjustment: Critical for proper piston-to-cylinder head clearance (approximately 0.040 inch).
- Crankshaft Shaft Seal: Replaced if significant oil leakage develops.
- Guide Cylinders: Removed to service rings and pistons.
- Connecting Rods: Bearing inserts, bushings, or wrist pins replaced if clearances are out of tolerance. Oil dippers must be oriented downward towards the oil sump.
- Main Bearings: Tapered roller design, lubricated by crankcase oil splash. No scheduled maintenance.
Safety Precautions:
- Always relieve internal pressure and isolate the compressor from external pressure sources before working on it.
- Ensure all electrical components are installed and grounded according to codes.
- De-energize and tag out electrical equipment before working on it.
- Do not operate without safety guards.
- Do not reset relief valves or pressure switches to higher than specified pressures.
- Avoid unauthorized alterations.
- Do not touch hot cylinder heads or discharge gas lines during operation.
- Never stick hands inside the distance piece when the unit is running, as metal slingers on piston rods can cause injury.
- All oxygen-wetted parts must be cleaned for oxygen service.
- Use only oxygen-compatible materials and grease in gas piping areas.
- Do not use flammable solutions for leak testing.
- The piston-to-cylinder head clearance adjustment is critical; insufficient clearance can cause the piston to hit the head.
- Incorrect installation of oil dippers can lead to insufficient lubrication and catastrophic failure.
The compressor is an AS9100C:ISO9001-2008 registered product, ensuring high quality.
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