GPC Calibrated Helium Leaks




The GPC Model Helium Calibrated Leak Standards have crimped stainless-steel capillary leak elements and are widely used to tune and calibrate helium mass-spectrometer leak detectors and leak testing systems. They are part of a family of Helium Calibrators offered by VTI including the GPP, GPPT and CLP Models detailed in other brochures. Together they cover a wide range of leak rates from 10-12 to 10-2 atm-cc/sec and larger. VTI’s experts are always eager to help you select the best model – technically and cost – for your application. Without obligation, of course.

Additional Information

The GPC Accu-Flow™ Helium Leaks, due to the capillary leak element, can be manufactured for larger leak rates than permeation-type leaks. They are often used therefore in calibrating detectors in the “gross leak” mode. Also, capillary-type leaks have a very low temperature coefficient of 0.2%/ °C, as compared to 3-4% for permeation-type leaks. This reduces the possibility of calibration error in applications where ambient temperatures vary widely. As compared to some leaks that are made with glass capillary leak elements, the GPC Leaks with their stainless steel capillaries are unbreakable.

In applications where these capillary-type leaks are exposed to dirt, water or oil vapor, clogging of the leak element can be a problem, particularly for leak rates of 10-6 atm-cc/sec and smaller. For this reason, the shut-off valve on the leak should be closed when not in use, especially when venting the vacuum system or detector to which it is attached. While GPC Leaks can be made without shut-off valves, it is not usually recom variance and will be as close as we can make it to your specified rate. The actual rate, as calibrated, will be recorded on the Calibration Tag and the Certifications.

As with all of VTI’s Helium Calibrators, the GPC Model Leaks are available with QF (NW, KF), pipe thread and many other types of attachment fittings, and are provided with Certifications of the NIST-traceable Calibrations performed in our A2LA Calibration Laboratory.

Why choose the GPC Calibrator?

WIDE LEAK-RATE CHOICE – 10-3 to 10-6 range
LONG TERM STABILITY – low depletion rate
UNBREAKABLE – stainless steel leak element
NEVER NEEDS REFILL – lasts for years
CLOGGING POSSIBLE – in unclean environments
MEETS ISO REQUIREMENTS – NIST-traceable, A2LA-accredited Calibration Certification

Ordering Information

The GPC Calibrators can be ordered for a specified Helium Leak Rate within a wide range of values. When ordering or requesting a quotation, please provide the Part Number, confirm the Fitting needed, and state the specific Leak Rate requested including your preferred leak-rate units. Also, please specify the Manufacturing Variance (“Tolerance”) that you can allow on that Leak Rate. The usual manufacturing variance is +/- 40% of the requested rate. An example specification is 2.0 x 10-5 atm-cc/sec +/- 40%. Alternatively, the allowable values as manufactured can be specified as 1 to 3×10-x, 4 to 6×10-x, or 7 to 9×10-x in a Leak Rate Range listed below.

Also, a “Special Range” manufacturing variance is available of +/- 15% of the requested rate. For this special variance, an “-SR” is added to the end of the Part Number and there is an additional cost. In all cases, the leak rate provided will be within the selected manufacturing variance and will be as close as we can make it to your specified rate. The actual rate, as calibrated, will be recorded on the Calibration Tag and the Certifications.

Part Number Build Up

The GPC Series Part Numbers are constructed as follows:


where X = the code for the Leak Rate Range required

where YYYY = the fitting required

where ZZZ = the code for the reservoir size

Valve Requirements – the addition of a Fill Valve is required on all leaks in the mid 10-6 range and larger due to the higher fill pressures. In these cases, -WFV is added to the end of the part number. For leaks without a shut-off valve, -NV is added.

Example Fittings Available

Please contact us for other fitting requirements.

Code: Description:
118T 1-1/8″ OD Port Tube
4FVCR ¼” Female VCR
4MVCR ¼” Male VCR
MCFF 1.33″ OD Mini Conflat Flange
2CFF 2.75″ OD Conflat Flange
½T ½” OD Tube
KF16 ¾” OD ISO Flange
KF25 1″ OD ISO Flange
KF40 1.5″ OD ISO Flange
118T/34T 1-1/8″ OD Tube with step to ¾” Tube
4MPT ¼” Male Normal Pipe Thread

Leak Rates Ranges Available and Example Part Numbers

Leak Rate Ranges Available for the GPC Code for Leak Rate Range (X) Code for Fitting (YYY) Sugg’ed Reservoir Size Code for Reservoir Size(YYY) Example Part Number
(Specify a value in the range)
1.0 to 9.9×10-3 atm-cc/sec 3 KF16 1000 1000DOT GPC-3-HE-KF16-1000DOT-WFV
1.0 to 9.9×10-4 atm-cc/sec 4 MCFF 1000 1000DOT GPC-4-HE-MCFF-1000DOT-WFV
1.0 to 3.0×10-5 atm-cc/sec 5 KF25 1000 1000DOT GPC-5-HE-KF25-1000DOT-WFV
1.0 to 9.9×10-5 atm-cc/sec 5 KF40 500 500DOT GPC-5-HE-KF40-500DOT-WFV
1.0 to 9.9×10-6 atm-cc/sec 6 118T 1000 1000DOT GPC-6-HE-118T-1000DOT-WFV
1.0 to 9.9×10-6 atm-cc/sec 6 1/2T 500 500DOT GPC-6-HE-1/2T-500DOT-WFV

Note: Larger and smaller flow rates are possible. However, with leaks smaller than 10-6 atm-cc/sec there is increased risk of plugging of the capillary and precaution in use should be taken. For all leak rates, the leak’s shut-off valve should be kept in the closed position when the leak is not in active use.

A fill valve is required for H2, CO, CH4, SO2, NE, KR, D2, XE and HE3. Mixed gas leaks may also need additional calibration points.

Additional information


1.0E-2 to 9.9E-2 atm-cc/sec, 1.0E-3 to 9.9E-3 atm-cc/sec, 1.0E-4 to 9.9E-4 atm-cc/sec, 1.0E-5 to 9.9E-5 atm-cc/sec, 1.0E-6 to 9.9E-6 atm-cc/sec, Unknown


1-1/8" OD Tube, 1-1/8" to 3/4" OD Tube, 1.33" OD Conflat Flange, 1/4" Female NPT, 1/4" Female VCO, 1/4" Female VCR, 1/4" Male NPT, 1/4" Male O-Seal, 1/4" Male VCO, 1/4" Male VCR, 1/4" OD Tube, 1/4" Swagelok Compression Fitting, 1/8" Female NPT, 1/8" Male NPT, 1/8" Male O-Seal, 2.75" OD Conflat Flange, 3/8" Male NPT, QF16 (KF16), QF25 (KF25), QF40 (KF40)


+/-10% of Target Leak Rate, +/-15% of Target Leak Rate, +/-20% of Target Leak Rate, +/-40% of Target Leak Rate – Standard, +/-5% of Target Leak Rate