Backflow Test Kits

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In 2019, through certifying thousands of students in backflow testing courses across the USA, it became evident that a simpler and more durable test kit was necessary for the industry. With other manufacturers creating digital kits, made of plastic, with more needle valves, we saw a different path. Working professionals like backflow assembly testers and hands-on workers in general, require tools that are durable, simple to use, manufactured and assembled in the USA. The concept for Kruger Instruments was born.

The newest version of the TK-2 has integrated the design with input from field testers and with the ASSE 1064 Standard requirements to provide an easy to use, water proof, +/- 0.2 psi accurate, and extremely durable ( all metal ) test kit. 

With backflow testers in mind, gauges do have to meet all of the required specifications, which have changed over the years but the most current and used document across the USA for backflow test kit functionality is the ASSE 1064-2020 product standard. ASSE has all of their product standards online for purchase and free reading here but we have a breakdown below on the critical items:

1.2.2.1 - On descending pressure, differential gauges shall have an accuracy of ± 0.2 psid - We worked with Orange Research to develop a production method  to meet this accuracy requirement, similar gauges produced by them before 2020 were only accurate to +/- 0.3 psid. Essentially they build the gauge head and then hook it to a computer that prints the dial according to measured readings, instead of printing the same dial on every gauge and adjusting the components to tolerance. Normally, the Orange Research bases we use to make the TK-2 come perfectly accurate from the factory when accuracy is verified through calibration ( meaning all test points on the gauge are 100% accurate or extremely close almost every time )

1.2.2.3 - Portable BFTKs shall indicate a full-scale pressure reading of 15.0 psid. Gauges designed to read a line pressure shall have a maximum range of 300.0 psi. The TK-2's Range is 0 - 15 psi on the differential gauge, and, for models which include the line pressure gauge, it has a range of 0 - 300 psi.

1.2.5.1 - Gauge must resolve 0.1 psi - the scale reads 0 - 15.0, with 1 psi lines and 0.2 psi lines, if pointer lands between two of the 0.2 lines, it is shown as the 0.1 in between ( between 3.2 and 3.4 lines is read as 3.3 psid ), otherwise lines read as shown

3.33 - If the pointer is bent after the gauge is laboratory tested, it fails. There is a pressure shock test required on section 3.7 that does 25 rapid pressurizations of the kit to 65 psi. The TK-2 Needles are much stronger and have less overall leverage for impact the closer the needle gets to it's pivot, thus preventing damage to the needle that similar products often would incur during the test or field use without the needle pin.

4.12 - Materials to be used in construction of these BFTK shall be bronze, which conforms to ASTM B61 or ASTM B62, ASTM B-584, ASTM B176, or 300 Series Stainless Steel, non-cast bronze

58% copper, brass which conforms to UNS C36000, Beryllium-Copper (Be-Cu) which conforms to UNS C17200, or plastics or anodized aluminum which provide equivalent performance - the TK-2 base is constructed from anodized aluminum, internal wetted components are stainless steel, with bronze fittings on all connections and brass needle valves. Maximum pressure rating on the aluminum body is 1500 psi ( ASTM B-61 and B-584 bronze alloys typically used in plumbing valves have a burst pressure of around 1200 psi )

Floating Zero - No diaphragm style gauges are accurate below 1.0 psi, the springs on the diaphragms aren't designed to be accurate below this minimum, and also don't need to be. We incorporated a floating zero where 1.0 psi is the lowest reading possible. Although other gauges pin at 0.0 psi and seem to read 0.1 increments all the way through 1.0 psi, when doing accuracy verification, all calibration technicians will see that below 1.0 psi they are wildly inaccurate, typically they pin at 0.0 with around 0.6 psi introduced to them on the descending. It is misleading and not good practice to have a gauge that can read 0.3 psi even though the pressure is actually closer to 0.8 psi, and often schools misinterpret the testing procedures for leaking check valves. If, when doing a test, the CV is clearly reading below 1.0 psi, you mark it as leaking, since values below 1.0 psi on an analog test kit are not accurate. The floating zero also indicates to the tester if the gauge needs calibration or repair, the pointer should read more or less in the exact center of the floating zero box, if the needle is significantly closer to one side, often this is an indicator that the gauge may need an accuracy adjustment. 

Water Proof - We added a water proof front housing, many comparable models use a friction fit front which allows water to condensate and cause damage to the kit over time and also making it hard to read the gauge due to fog from condensation, specifically in sunny and dry environments. 

Calcification - Water can cause deposits of calcium to accumulate on the internal mechanisms of the gauge. "Hard Water" or water with dissolved limestone, gypsum, and other calcium containing minerals can leave deposits over time and cause valves and gauges to malfunction. Water that is introduced to the gauges is normally before any water softeners. In order for calcification to occur, hard water must be in non-stop contact with the components over a significant period of time. With a 2 valve arrangement, the design process has minimized the calcification risk, since the kit is easier to completely drain and often does not stay water logged even if not properly drained. Other kits have more complex arrangements which are more likely to trap water and consequently have a higher risk of calcification. Often it is easier to store larger kits with the needle valves closed to avoid spontaneous drops of water in the case. The anodization process for the aluminum body, and the 2 valve arrangement, for the TK-2 controls the level of calcification to a near zero minimum.

Freezing - Similar to calcification, the 2 valve arrangement also minimizes freezing, since the diaphragm is smaller and there are fewer attachments with only 2 valves, even with the needle valves closed, water will typically have enough space to expand out the bottom upon freezing. We have calibrated TK-2s that were frozen solid, just wait for it to thaw, drain the water, and the gauge functions perfectly. Also the kit is very easy to drain due to the size and orientation of the attachments, which we recommend draining and not storing in freezing temperatures.