Robinair Models 15234 - Manual (Page 4)

© 2000, SPX Corporation
4
USING THE GAS BALLAST (Vented Exhaust)
All Robinair high vacuum pumps feature a gas ballast for more thorough
evacuation and longer pump life. As vapors from an A/C or refrigerant system
containing more than the average amount of moisture pass through a vacuum
pump, they condense into liquid, and combine with the vacuum pump oil.
When these vapors mix with the oil, it becomes contaminated, raises the vapor
pressure of the vacuum pump oil, and reduces the pump's ability to reach its
ultimate attainable vacuum. Opening the ballast valve purges a small amount of
atmospheric air through the exhaust chamber. This extra volume of air mixes
with the vapors from the A/C or refrigerant system, prevents them from being
condensed, and helps them to be exhausted from the pump in vapor form.
After the pump has started, the gas ballast valve (see diagram on page 2) should
be opened until the system has reached approximately 1000 microns. At this
time, close the valve to allow the pump to pull its ultimate vacuum level. The
gas ballast valve may be opened or closed at any time during pump operation.
The valve is fully open at two turns, counterclockwise.
SHUTTING DOWN THE PUMP
Follow these procedures when shutting down your pump to ensure long life and
easy starting:
1. Shut off all gauges to the A/C system.
2. Close any valve beteween the pump and the A/C system.
3. Turn off the pump. Open the inlet port to the atmosphere immediately at
shutdown.
4. Cap the inlet port immediately to prevent any contamination or loose
particles from entering the port.
For maximum performance, Robinair recommends charging vacuum pump oil
after each use. Use only a high quality oil. Robinair recommends its Premium
High Vacuum Pump Oil, which has been specially blended to maintain
optimum viscosity at high and low operating temperatures.
CHANGING THE OIL
1. Verify the pump is warmed up and the inlet is opened to atmosphere.
2. Disconnect the pump from the A/C electrical power source.
3. Remove the black operating exhaust plug from the top of the pump
reservoir.
4. Hold the pump upside down, tilting it forward and backward to drain all
the oil from the reservoir into a suitable container.
Vacuum Pump Models 15234/15226/15296
5
Note: If the drained oil is badly contaminated, the pump may need to be
flushed. If flushing is necessary, run the pump (CAUTION: To prevent
damage to the pump, do not run the pump more than 30 seconds
without any oil.) and slowly pour clean oil through the pump inlet (being
careful not to slug, or bog down, the pump). Drain the oil, and repeat this
procedure as necessary before going to Step 5.
5. Refill the pump reservoir to the “OIL LEVEL” line on the sight glass with
fresh Robinair High Premium Vacuum Pump Oil.
6. Replace the black operating exhaust plug.
CLEANING THE PUMP
Clean the pump with soap and water only. Do not use commercial cleaners that
contain degreasing agents that can damage polycarbonates. The pump handle
and base are made of Lexan*, one of the toughest polycarbonate plastics
available. However, it is sensitive to degreasing agents.
*Lexan is a registered trademark of General Electric
TROUBLESHOOTING TIPS
Before returning any Robinair vacuum pump, in or out of warranty, review the
following troubleshooting guide:
Failure To Pull Good Vacuum
1. Verify the gauge and connections are leak-free and in good condition. You
can confirm this by monitoring vacuum with a thermistor vacuum gauge
while applying vacuum pump oil at connections or suspected leak points.
The vacuum will improve briefly while the oil seals the leak, then revert to
the previous level.
Note: Checking pump vacuum through a charging hose is not recommended.
Refrigerant and other contaminants contained in the hose may adversely affect
the vacuum reading.
2. Verify the pump oil is clean. A badly contaminated pump may require
several oil flushes (see “Changing the Oil”) before you are able to reach the
rated vacuum level.
3. Verify the oil is at the proper level. For proper vacuum operation, the oil
must be level with the sight glass oil line. Overfilling will not affect vacuum
operation, but may result in oil blowing from the exhaust during free air
operation.
4. Verify the gas ballast valve is fully closed.