Kruger Instruments - Calibration Services

Bring your kit to one of our courses and we will calibrate it on site. Let me know at 917-887-5613 via text to confirm availability. Cash Preferred.

Chantilly, VA   -   Richmond, VA   -   Fredericksburg, VA   -   Newport News, VA   -   Syracuse, NY   -   Eatontown, NJ   -   Hammonton, NJ   -   Cherry Hill, NJ   -   Milwaukee, WI   -   Rancho Cucamonga, CA   -   Bellflower, CA ( Los Angeles )   -   San Jose, CA   -   San Diego, CA   -   Panama City, FL   -   Augusta, GA   -   Sarasota, FL   -   Brockton, MA

If you are in the NYC area, we can also do calibrations in Manhattan ( 1st Ave / 7th Street ) or you can mail them in

Most jurisdictions that regulate backflow preventer testing require that the instruments be "calibrated" periodically. Over time, using the gauge causes the diaphragm adjustment mechanisms in analog gauges to move around, loosen, etc., such that the needle reading compared to introduced pressure will change over time. The gauge falls out of accuracy, and will not read the correct values. An authorized calibration technician will then test the gauge for accuracy against another, more accurate, gauge ( usually digital ) and then move the adjustment mechanisms on the test kits until the needle is reading the proper values.

Our standard calibration and adjustment service for a differential pressure gauge is a verification of accuracy against an NIST traceable reference, including adjustment. This service includes everything required to re-calibrate it to within acceptable tolerances. The gauge has to be "in working order," and our standard calibration service, although including adjustment, does not include repair, acid cleaning, or replacement of any pieces. Calibration is only offered for Backflow Test Kits and only those that are seeking calibration of +/- 0.2 PSI on the descending scale ( the minimum accuracy required by USC, ASSE, AWWA, and pretty much all state / local jurisdictions )

The bare minimum regulatory requirements are almost always worded such that you cannot perform a backflow test if the gauge used has not had an accuracy verification in the last 12 months. The easiest way to maintain your test kit is to have its accuracy verified both periodically, and if you see something obviously wrong with the readings, maybe all RPZs you test have 5.3 psi for Check Valve #1 when normally it would read 7.0 psi or so and a lot of DCVs are failing, this could indicate that the gauge is reading lower PSI than it should. For TK-2s, you can usually tell if one is out of calibration by the location of the needle pointer at zero, it should be more or less in the center of the floating zero, if too far left or right, your gauge might be out of calibration. 

Mail in your gauge for full calibration and adjustment. Gauge must be in working order ( not leaking or damaged ) in order to facilitate the calibration. Ship to Kruger Instruments, 108 First Ave, UPS Store #408, New York, NY 10009.

You can pay the $100 charge to calibrate with a card following the below link. If you have more than one gauge, you can adjust the quantities on the left side of the payment window there is a drop down menu.

MAIL-IN CALIBRATIONS REQUIRE CUSTOMER SUPPLIED RETURN SHIPPING, just purchase return shipping when shipping the gauge to us, mostly for concerns about liability if damage occurs during shipping. Gauges can be damaged during shipping if not properly packaged. We recommend shipping all packages UPS and getting some level of insurance, often they can make the packaging for you using bubble wrap and appropriately sized boxes to prevent shipping damage. If you send in a gauge without return shipping and just say "Oh they wouldn't let me get return shipping," it is very likely we will refuse to mail it back as a violation of our terms and conditions, and we can have it available for pick up at the UPS Store on 108 First Ave in Manhattan ( 1st Ave and 7th street ). 

A copy of the calibration report will be in the returned package. 

PAY THE $100 MAIL-IN CALIBRATION FEE

The kits are designed to be drained after each use, but often people do not drain them properly. If you leave a hose connected, especially if you loop the hose from the bottom to the top of the high valve, if it's full of water, often scum develops inside the test kit and can effect the needle pointer reading. If your kit is reading 1.0 or similar with nothing attached to it, i.e. the needle is not pointing within more or less the center of the zero box, it is likely you have this to some extent. We offer a free acid wash / flush treatment which resolves this issue, essentially we take the calibration head part off the kit, pressurize the kit to the max, fill it with coffee machine descaler which is basically just low grade acid, then let it sit and then slightly pressurize the kit and move the needle back and forth. Then do a hot water flush through the connections. This removes the scum very effectively and puts the zero pointer back where it should be. If you bring a kit in for on site calibration that has a zero pointer that is close to 1.0, we cannot calibrate it on site in this condition, you have to mail it in and do the acid wash & flush treatment, which is included in the standard mail in offering.