ULVAC Sorption and Getter Pumps
Sorption pumps achieve roughing vacuum without oil by adsorbing gas molecules onto zeolite molecular sieve cooled in liquid nitrogen. No moving parts, no oil, no vibration. Essential where hydrocarbon contamination of the process chamber is unacceptable. The ULVAC PSM-010B has an NW25 inlet. Two units in series can rough from atmosphere to below 1 Pa before starting a turbomolecular or ion pump.
Part Numbers
Operating Principle
The PSM-010B contains approximately 200 g of 5A zeolite. Immersion in liquid nitrogen dramatically increases the surface adsorption capacity. Nitrogen, oxygen, water vapour, CO2, and argon are efficiently adsorbed. Helium and hydrogen are NOT adsorbed efficiently at liquid nitrogen temperature and remain in the system. Supplement with a NEG cartridge or titanium sublimation pump if these gases must be reduced.
Commissioning and Operating Procedure
- Close the inlet valve between the sorption pump and the vacuum system
- Fill the dewar with liquid nitrogen — submerge the pump body cylinder; do not cover the inlet flange
- Allow 15 minutes minimum cool-down before opening the inlet valve
- Open the inlet valve slowly while monitoring the vacuum gauge
- When pumping rate slows, close the inlet valve — zeolite approaching saturation
- For two-stage roughing: cool the second pump 15 minutes, then open its inlet valve
- When target rough vacuum achieved, close inlet valve and start the high-vacuum pump
Regeneration
- Confirm inlet valve fully closed
- Remove dewar or allow pump to warm to room temperature (20 to 40 minutes)
- Open vent valve slowly to release gas to atmosphere — never back into the vacuum system
- Once fully vented and at room temperature, ready for next cycle
Fault Diagnosis
| Symptom | Cause | Action |
|---|---|---|
| Pressure does not drop below 1000 Pa | Insufficient cool-down; LN2 level low | Wait full 15+ minutes after LN2 fill; top up LN2 |
| Reduced capacity vs previous cycle | Zeolite not fully regenerated | Allow full warm-up and complete venting |
| Rapid pressure rise after closing inlet | Zeolite saturated; moisture in gas | Shorten pumping cycle; verify process gas is dry |
| Leak at inlet flange | NW25 o-ring damaged | Replace inlet o-ring; clean flange faces |
| Permanently reduced capacity | Zeolite contaminated with solvents or water | Workshop bakeout at 300 C in air, or zeolite replacement |
| He/H2 background not reduced | Expected — zeolite does not pump these gases at LN2 temperature | Add NEG cartridge or titanium sublimation pump |
Maintenance
- NW25 inlet o-ring: replace at each system open or annually
- Dewar: check for insulation loss (abnormal external frosting); replace dewar if insulation failed
- After approx 500 cycles or clear capacity loss: arrange zeolite replacement or workshop bakeout regeneration
- Heater element (part 200000180400): replace if resistance out of specification
- Alloy filament set (part 210004540500, 6 pcs): replace when getter capacity exhausted
- Molecular sieve material (part 210004540100, 5A, 1 kg): available for zeolite replenishment
Training
Operator training: LN2 handling and PPE, cool-down and venting procedure, two-stage roughing sequence, integration with TMP startup, recognising zeolite capacity degradation. Maintenance training: o-ring replacement, zeolite inspection, bakeout regeneration. Contact mail@ulvacheliot.com — provide: pump model, number of attendees, site location.
Service Enquiry
Email mail@ulvacheliot.com — provide: pump model (PSM-010B), serial number, fault or items required. Available: NW25 o-ring, alloy filament set (210004540500), heater element (200000180400), molecular sieve (210004540100).