RLS Calibrated Refrigerant Leaks


The RLS Refrigerant Leak Standards developed by VTI have been in use worldwide for over 10 years as the Standard for calibrating sniffer-type refrigerant leak detectors. These Leaks are available for all old and new Refrigerants and a wide range of leak rates from 0.01 to over 10 oz/yr. Also, each RLS has a 10:1 adjustable leak rate range (such as 0.1 to 1.0 oz/yr). VTI’s calibrations of each of these Standards are Certified to be NIST-Traceable and A2LA Accredited, and indeed they form the basis of traceability for most of the manufacturers of refrigerant detectors in the world.

Additional Information

The RLS has a reservoir of liquid refrigerant that is interconnected with a valve to the vapor reservoir to provide a convenient, long time supply of vapor for the Leak. Depending on use patterns and QA requirements, these Leaks are typically sent to VTI for refill and recalibration after one to three years of use. Unlike the fragile glass capillaries sometimes used by other manufacturers, the RLS uses a crimped stainless-steel capillary leak element that is unbreakable.

To provide the adjustable leak-rate feature, the RLS is calibrated by VTI at 3 pressures yielding 3 leak rates, and an individualized graph of the pressure vs. leak-rate data is included in the calibration Certifications for the Leak Standard. Any specific rate within the adjustable range can be selected using this calibration curve and then adjusting the pressure in the vapor chamber to the value corresponding to that rate on the calibration graph.

The pressure in the vapor chamber is increased by (slowly) opening the valve connecting the two reservoirs, and is decreased by opening the exhaust valve on the vapor reservoir. The pressure gauge connected to the vapor reservoir is used in the calibration of the RLS, and subsequently in adjusting the pressure to the selected value to preserve the NIST-traceability of the leak rate when calibrating a leak detector.

Why choose the RLS Calibrator ?

  • WIDE LEAK-RATE CHOICE – 0.01 to 10 oz/yr
  • ACHIEVE EXACT LEAK RATES – your test point
  • LONG TERM STABILITY – low depletion rate
  • 10:1 ADJUSTABLE LEAK RATE RANGE – use any specific rate within the range
  • UNBREAKABLE – metal capillary leak element
  • NO FALSE READINGS – no large dead spaces
  • EASY PROBE LOCATION – for repeatable results
  • MEETS ISO REQUIREMENTS – NIST-traceable, A2LA-accredited Calibration Certification

Using the Calibrator

To calibrate a refrigerant leak detector using the RLS Refrigerant Leak Standard, the leak rate of the RLS is first adjusted to the desired value for the calibration. Using the calibration graph of pressure vs. leak rate, as previously described, the pressure value corresponding to the desired leak rate is determined from the graph. The pressure in the vapor chamber, as measured by the gauge attached to it, is then adjusted to that value using either the “Increase” or “Decrease” Valve of the RLS. To increase the pressure in the vapor chamber to a selected value, the Increase Valve, on the right in the photograph, is opened to admit vapor to the vapor chamber from the liquid reservoir (which has a vapor “head” corresponding to the vapor pressure of the particular refrigerant). To lower the pressure in the vapor chamber to a selected value, the Decrease Valve is opened to exhaust vapor to the atmosphere.

The refrigerant vapor then leaks from the vapor chamber to the atmosphere through the RLS’s stainless-steel capillary leak element at the selected as-calibrated flow rate. The capillary leak element is surrounded by a protective stainless steel tube that protrudes from the vapor chamber to the left of the pressure gauge in the photograph. The end of this tube has a machined, tapered recess designed to receive the tip of the sniffer-detector probe and provide secure collection of the refrigerant flow/leak rate from the capillary leak element. To calibrate the leak detector to this selected leak rate, the sniffer probe tip is placed in the tapered recess, withdrawn, and replaced until a repeatable detector response signal is obtained. The detector signal scale is then calibrated to this NIST-traceable leak rate.

Reliable Calibration of the Sniffer Leak Detector is fundamental to effective operation. The “point-source” design for the gas flow assures that excessive calibration gas will not accumulate in “dead spaces” to cause erroneous high readings during detector calibration, which can later result in “passing” bad product.

Ordering Information

The RLS Calibrators can be ordered for almost all Refrigerants and for 10:1-adjustable leak rate ranges that cover all common rates. For an order or RFQ, please provide the Part Number and also specify the Leak Rate Range and Units that you require using the tables below. If you have any technical or ordering questions, please contact us for assistance.

Part Number Build Up

The RLS Series Part Numbers are constructed as follows:


where XXXX = the “R” code for the Refrigerant requested

where YYYY = the code (the central leak rate) for the adjustable leak rate range requested

where LFT = the code for the standard sniffer-probe interface tube that surrounds the capillary leak element and provides the recess for the sniffer probe during detector calibration

where ZZZ = the special code (LGF) for an optional customized scale on the pressure-gauge face, and/or the special code (WFV) for a non-standard fill valve required on the liquid refrigerant reservoir for some refrigerants, as identified in the table above. If neither applies, there is no entry after LFT; if both apply, there are two entries.

Common refrigerants are listed in the table below and others are available. Also listed below are the codes (central leak rates) for the various Adjustable Leak-Rate Ranges that are available expressed in the three Leak Rate Units most commonly used.

The LGF code is used to add an optional scale to the pressure-gauge face that reads in actual leak rate units (e.g., oz/year) instead of pressure units. This customized scale is computer printed based on the calibration data and is pasted over the inner “bar units” scale of the gauge. The outer scale of the gauge is in “psi” and remains visible. Instead of this option, most RLS users read the gauge in the more precise pressure units and use the pressure vs. leak-rate graph provided.

Refrigerants Available

R-507 (AZ-50)
R-290 (Propane)*
R-600 (Butane)*
R-600A (Isobutane)*
SF6 (Tracer Gas)*

*Indicates Special WFV fill valve required

Codes for Various Adjustable Leak-Rate Ranges

Common Units Code For Part Number  (central leak rate or exponent) Leak Rate Range
Ounces/year (OZ) 0.05 OZ 0.01 t0 0.1 0z/yr
Ounces/year (OZ) 0.10 OZ 0.05 to 0.5 oz/yr
Ounces/year (OZ) 0.35 OZ 0.07 to 0.7 oz/yr
Ounces/year (OZ) 0.50 OZ 0.10 to 1.0 oz/yr
Ounces/year (OZ) 1.00 OZ 0.25 to 2.5 oz/yr
Ounces/year (OZ) 5.00 OZ 1.00 to 10 oz/yr
Grams /year (G) 1.50G 0.3 to 3 g/yr
Grams /year (G) 3.0 G 1.5 to 15 g/yr
Grams /year (G) 10G 2.0 to 20 g/yr
Grams /year (G) 15G 3.0 to 30 g/yr
Grams /year (G) 30G 7.5 to 75 g/yr
Grams /year (G) 150G 30 to 300 g/yr
atm-cc/sec E6 1.0 to 9.9 x 10-6
atm-cc/sec E5 1.0 to 9.9 x 10-5
atm-cc/sec E4 1.0 to 9.9 x 10-4