GPP Calibrated Helium Leaks




These GPP Model Helium Calibrated Leak Standards have glass-permeation type leak elements and are the most common ones used to tune and calibrate helium mass spectrometer leak detectors, leak testing systems and vacuum systems. They are part of a family of Calibrators including the GPPT, GPC and CLP Models offered by VTI that cover leak rates from 10-12 up to 10-3 atm-cc/sec and larger. Those models are detailed in other brochures, and 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 GPP Accu-Flow™ Calibrated Leaks are based on the principle that helium flows through certain materials at a measurable rate depending on the material thickness, driving pressure and temperature. Depending on the leak rate required in the GPP Leaks, the permeation material is Pyrex or Quartz.

The GPP Leaks feature an all-welded stainless steel construction for reliability. Most leaks require a shut-off “isolation” valve to zero the leak signal during tuning and calibration. VTI offers the GPP Leaks both with and without a Teflon®-packed stainless steel shut-off valve. The inlet port of the brand of leak detector or vacuum system determines the termination of the leak. The most common termination of the GPP Leaks is a 1-1/8″ diameter tube which mates directly to many Varian, Veeco and VIC leak detectors. All leaks are available with QF (NW, KF) and many other types of fittings.

All GPP Leaks are provided with certifications of the NIST-traceable calibrations performed in our A2LA-accredited Calibration Laboratory.

Why choose the GPP Calibrator?

WILL NOT CLOG – permeation leak element
LONG TERM STABILITY – low depletion rate
WIDE LEAK-RATE CHOICE – 10-5 to 10-9 range
NEVER NEEDS REFILL – lasts for years
SIMPLE TO OPERATE – minimal user training
MEETS ISO REQUIREMENTS – NIST-traceable, A2LA-accredited Calibration Certification

Ordering Information

The GPP 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 2.0×10-8 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 GPP 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
8T 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 GPP 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 9.9×10-5 atm-cc/sec 5  KF25  1000  1000DOT  GPP-5-HE-KF25-1000DOT-WFV  
1.0 to 9.9×10-6 atm-cc/sec 6  KF40  500  500DOT  GPP-6-HE-KF40-500DOT-WFV  
1.0 to 9.9×10-6 atm-cc/sec 6  118T  500  300DOT  GPP-6-HE-118T-300DOT-WFV  
1.0 to 3.0×10-6 atm-cc/sec 6  1/2T  300  300DOT  GPP-6-HE-1/2T-300DOT  
1.0 to 9.9×10-7 atm-cc/sec 7  KF16  110  (Blank)  GPP-7-HE-KF16  
1.0 to 9.9×10-8 atm-cc/sec 8  2CFF  110  (Blank)  GPP-8-HE-2CFF  
1.0 to 9.9×10-9 atm-cc/sec 9  MCFF  110  (Blank)  GPP-9-HE-MCFF  

Additional information


1.0E-5 to 9.9E-5 atm-cc/sec, 1.0E-6 to 9.9E-6 atm-cc/sec, 1.0E-7 to 9.9E-7 atm-cc/sec, 1.0E-8 to 9.9E-8 atm-cc/sec, 1.0E-9 to 9.9E-9 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, 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