Chiller refrigerant pressure gauges are not interchangeable with standard industrial gauges. Each refrigerant circuit — high-side discharge, low-side suction, and maintenance vacuum — demands a different pressure range, Bourdon tube material, and connection standard. This guide covers gauge selection for R-22, R-134a, R-410A, R-407C, and CO2 (R-744) chiller systems, with decision points for range, accuracy class, and wetted materials.
Chiller refrigerant pressure gauges must match the saturation curve of each refrigerant. The table below gives the typical high-side and low-side pressures at common operating conditions:
| Refrigerant | High-side (condensing, 45°C) | Low-side (evaporating, 5°C) | Recommended gauge range |
|---|---|---|---|
| R-22 | ~17 bar (246 psi) | ~5.8 bar (84 psi) | High: 0–25 bar | Low: 0–10 bar or compound |
| R-134a | ~11.6 bar (168 psi) | ~3.5 bar (51 psi) | High: 0–16 bar | Low: compound –1 to 10 bar |
| R-410A | ~26.5 bar (384 psi) | ~9.0 bar (131 psi) | High: 0–40 bar | Low: 0–16 bar or compound |
| R-407C | ~24.8 bar (360 psi) | ~8.2 bar (119 psi) | High: 0–35 bar | Low: 0–16 bar |
| CO2 (R-744) | Up to 130 bar (1885 psi) | ~27 bar (392 psi) | High: 0–160 bar SS | Low: 0–40 bar SS |
A gauge sized at 130–150% of maximum operating pressure gives the best accuracy across normal working range while protecting the Bourdon tube from pressure spikes.
The high-pressure side of a chiller refrigerant circuit is where the compressor discharges hot gas into the condenser. Key selection criteria:
The chiller refrigerant low pressure gauge monitors the evaporator side where refrigerant boils at low temperature and pressure. Sub-atmospheric pressures occur during pump-down and commissioning:
For CO2 systems the low-side operating pressure at +5°C evaporating is already ~27 bar, so a low-side gauge rated to at least 40 bar is required — a standard HVAC compound gauge is completely undersized.
CO2 refrigeration operates at pressures 5–8× higher than HFCs. A standard HVAC manifold gauge set is dangerous on a CO2 chiller. Requirements:
Manogauge supplies stainless steel CO2 refrigerant pressure gauges in 0–100, 0–160, and 0–250 bar ranges, with ATEX option for ammonia–CO2 cascade systems.
Get CO2 Pressure Gauge Quote ->→When placing an RFQ for chiller refrigerant pressure gauges, provide these parameters to avoid back-and-forth clarification:
Manogauge OEM chiller refrigerant pressure gauges are available as private-label assemblies for HVAC equipment manufacturers. Standard lead times are 15–25 days for OEM volumes, with express 7-day service for certified stainless steel CO2 gauges.
Related guides: A2L R-454B refrigerant pressure gauge selection and ammonia refrigeration pressure monitoring cover adjacent refrigerant gauge specifications.
Send Chiller Gauge RFQ ->→High-side, low-side and service gauge RFQs for HVAC/R and chiller systems.
Liquid-filled pressure gauge supplierUse for compressor vibration, pulsation and machine-room service panels.
No. Standard HVAC brass manifold gauges are rated to approximately 45 bar maximum. CO2 (R-744) chiller high-side pressures can reach 130 bar or above in transcritical operation. Using an undersized gauge is a safety hazard. Always use stainless steel gauges rated to at least 160 bar, designed specifically for CO2 refrigerant service.
A low-pressure chiller gauge measures refrigerant suction-side pressure — typically 0 to 10 or 16 bar — during normal operation. A torr vacuum gauge is used during system evacuation before refrigerant charging and must resolve to 50 microns (0.05 Torr) or better to confirm moisture removal. Bourdon tube pressure gauges cannot resolve vacuum at this level; electronic thermocouple or Pirani gauges are required for torr-range measurements.
For R-410A: high-side gauge 0–60 bar, Class 2.5 accuracy minimum (Class 1.6 for panel instruments), brass or stainless steel, 1/4" SAE flare or 1/4" NPT connection. Low-side: compound gauge –1 to +16 bar or a 0–16 bar gauge if the suction does not go below atmospheric. Glycerine filling is recommended if the compressor creates pulsation.
Annual calibration is standard practice for chiller machine-room gauges used in charge verification or fault diagnosis. Glycerin-filled gauges typically maintain accuracy longer than dry gauges because fill dampens compressor micro-vibration. Gauges used only for visual monitoring during normal operation may follow an extended 2–3 year cycle if plant risk assessment permits.
100 mm nominal dial is the minimum for readability at arm's length in a plant room. EN 837-1 accuracy class 1.6 suits routine monitoring; specify class 1.0 for gauges used during commissioning, leak checks or refrigerant charge verification. For low-side gauges reading below 5 bar, verify that the scale graduation spacing is adequate — a 0–10 bar range on a 100 mm dial reads more clearly than a 0–16 bar range at the same nominal size.