1. How can I select the right pump cfm?The following guidelines are for domestic through commercial applications.
| System size (tons) |
Pump cfm |
| 1-10 |
1.5 |
| 10-15 |
2.0 |
| 15-30 |
4.0 |
| 30-45 |
6.0 |
| 45-60 |
8.0 |
| 60 and above |
11.0 |
2. How much of a vacuum should I pull?A properly evacuated system is at 2500 microns or less. This is 1/10 of one inch and impossible to detect without an electronic vacuum gauge. For most refrigeration systems, ASHRAE recommends pulling vacuum to 1000 microns or less. Most system manufacturers recommend pulling to an even lower number of microns between 300 and 500.
3. Do I connect an electronic vacuum gauge to the system or pump?To monitor evacuation progress, connect it to the system with a vacuum/charge valve.
4. Why does the gauge micron reading rise after the system is isolated from the vacuum pump?This indicates that water molecules are still detaching from the system interior surfaces. The rate of rise indicates the level of system contamination and if evacuation should continue.
5. Does extension cord length affect performance?Increased length can decrease voltage, so use this as a voltage guide for selecting wire gauge.
| Distance |
Wire Gauge |
| 25' |
16 |
| 50' |
14 |
| 100' |
12 |
6. How can I speed evacuation?A. Use clean vacuum pump oil. Milky oil is water saturated and limits pump efficiency.
B. Remove valve cores from both high and low fittings with a vacuum/charge valve tool (link to product) to reduce time through this orifice by at least 20%.
C. Evacuate both high and low sides at the same time. Use short, 3/8" diameter and larger hoses.
D. SuperEvac Systems can reduce evacuation time by over 50-60%. SuperEvac pumps are rated at 15 microns (or less) to pull a vacuum quickly.
E. Use a heat gun (link to product).
7. How can I properly maintain my pump?A. Change the oil after every use while the oil is still hot, because contaminants are still in suspension and will be removed with the oil. If contaminants cool, solidify and stay in the pump, they lower vacuum efficiency. In extreme cases, the oil stops lubricating and the pump seizes. The only way to determine oil condition is to test vacuum pulled with an electronic vacuum gauge. Contamination cannot be determined by oil color.
B. When finished with the pump, replace the tethered caps on the intake fittings to keep out moisture and contaminants.