VSLC Calibrated Helium Leaks


The VSLC Leak Standards have been developed specifically to calibrate sniffer leak detectors. The VSLC model is manufactured with a capillary leak element that provides good service in most environments in the usual range for “Sniffing” of 10-3 to 10-6 atm-cc/sec. It should be noted, however, that the capillary is susceptible to clogging in dirty environments and at very small leak rates. With the capillary leak element, the VSLC Calibrators can be used for the larger leak rates of 10-3 and higher, and they have a very low temperature coefficient of 0.2% per °C, which is convenient for applications with wide temperature variations.

Primarily developed originally for calibrating Helium sniffer-type leak detectors, this model is used also to make Calibrators of many other gases and gas mixtures such as hydrogen or helium in nitrogen.

Additional Information

Why choose the VSLC Calibrator?

UNBREAKABLE – stainless steel capillary leak element
ADJUSTABLE LEAK RATE – each has a 10:1 leak-rate range
CAN BE SET TO AN EXACT LEAK RATE – without the usual manufacturing variance
NO FALSE READINGS – no large dead spaces
EASY PROBE POSITIONING – for repeatable results
MEETS ISO REQUIREMENTS – NIST-traceable, A2LA-accredited Calibration Certification

Using the Calibrator

To calibrate a Helium Sniffer Leak Detector, the operator places the tip of the sniffer probe briefly into the tapered recess at the point source of gas flow of the VSLC. The leak-rate reading of the Detector is then adjusted to the Leak Rate of the Calibrator, as provided by VTI on the Calibration Tag. A second reading is obtained in the same way to assure the calibration of the detector.

You should compare the VSLC periodically to another Calibrated Leak if available, and return it to VTI for recalibration in accordance with your Quality Assurance/ISO schedule requirements.

Ordering Information

The VSLC Calibrators can be ordered for various adjustable leak-rate ranges commonly used for sniffer-type leak detection. When ordering or requesting a quotation, please provide the Part Number and also specify the Approximate Leak-Rate Range requested including your preferred leak-rate Units (for example, “approximately 1 to 9×10-5 atm-cc/sec”). The Range specification is “approximate” because the minimum and the maximum value of the range will vary slightly for individual leaks due to the Manufacturing Variance. The leak-rate range available for each VSLC Leak is approximately a factor of 10, so the leak-rate range should be requested as approximately 1 to 9×10-x atm-cc/sec.

A leak-rate range extending between two decades can also be requested, such as from 5×10-6 up to 5×10-5 atm-cc/sec. (This is also an appropriate way to order a VSLC if you want to be able to obtain an exact leak rate of 1.0 x 10-5 atm-cc/sec.) An alternative specification is to identify the “Central Leak Rate” for a VSLC Leak, such as 5 x 10-5 atm-cc/sec, and VTI will build the Leak to provide that leak-rate at a mid range pressure on the 400-psig gauge. Using additional calibrations at a lower and higher pressure, the total leak-rate range of the Leak then extends above and below this central value. For each VSLC Calibrator, it is noted that exact leak rates like 4.5 x 10-5 can be obtained within its available range.

Without requiring specification, the VSLC Model Calibrators always have a fill/exhaust valve to allow the users to exhaust gas from its 110 cc reservoir to lower the leak rate, or to refill the reservoir to a higher pressure (using their clean gas supply) to increase the leak rate. The 400-psig pressure gauge on the standard VSLC model is used in VTI’s NIST-traceable Leak-rate Calibrations and preserves the NIST-traceability of the calibration for the user as the pressure and leak rate are varied.

Various leak-rate units can be specified and the calibration data will then be reported in the units requested. Please contact us for assistance if you have any questions or want a customized VSLC Leak.

“Special Orders” are everyday products for us! Just let us know what you need!


The most commonly used gases other than Helium are mixed gases, such as helium-nitrogen, for which the Gas Code is always: MIX. The composition of any mixture then needs to be specified in detail. Other common gases with their Codes are: Nitrogen(N2), Argon (AR), and Methane (CH4).

Please consult with our Calibrated Leak Technical Staff regarding these custom products.

Part Number Build Up

The Part Numbers for VSLC Sniffer Calibrators for gases other than Helium are constructed as follows:


where X = the code for the Leak Rate “Decade” within which an adjustable range of leak-rates is being requested

where 3P designates three calibration points for any gas other than Helium

where AA designates the gas requested

Leak-Rate Ranges and Part Numbers for VSLC Model Leaks

Examples of Requested Leak-Rate Ranges: Leak-Rate Code (X): Example Part Number:
1 to 9×10-3 atm-cc/sec 3  VSLC-3-3C-HE 
1 to 9×10-4 atm-cc/sec 4  VSLC-4-3C-HE 
5×10-4 to 5×10-5 atm-cc/sec 4/5  VSLC-4/5-3C-HE 
1 to 9×10-5 atm-cc/sec 5  VSLC-5-3C-HE 
3×10-5 to 3×10-6 atm-cc/sec 5/6  VSLC-5/6-3C-HE 
1 to 9×10-6 atm-cc/sec1 to 9×10-6 atm-cc/sec (for Argon) 6 6  VSLC-6-3C-HE VSLC-6-3P-AR