Disconnect pump from system.
Measure vacuum pressure at pump inlet with thermocouple or McLeod Gauge
1. If you do not have a good gauge borrow or buy
2. Check inlet port for cracks in seal or reset
NW fitting and clamp.
A. Inspect O'ring
on NW centering ring for cuts wear.
3. Turn pump on and wait 15 -20 minutes 1 hour is
A. Read pressure on
gauge. Compare with stated pressure of pump. Gauge limitations
and ambiguities understood. A good 2 stage pump should show less
than .001 micron on untrapped McLeod and 5-7 micron ofr better on
thermocouple gauge. HyVac single stage pumps are 10 to 40 micron
4. Write down pressure reading of pump.
This is what the pump is capable of vacuum pressure
5. Your system should be added and checked piece
6. Pressure attained at the pump inlet is
what you are capable of attaining on your system. Anything less is a
leak. Increasing the size of system expands the time to get to
"ultimate pressure" that you have written down.
Vacuum Unit Conversion Chart