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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.
Many iterations of test kits came out. Some with 0-10 scales in order to provide more accuracy, some with single valve or three valve arrangements. 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 product standards 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.
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. Range is 0-15psi on the differential gauge, and for models which include the line pressure gauge it has a range of 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 - This is why a needle pin is necessary, if when doing the test, the pointer is bent, the gauge will not pass their laboratory test. There is a pressure shock test required on section 3.7 that does 25 rapid pressurizations of the kit to 65 psi, without the end of line needle pin the pointer will almost certainly be bent after 25 rapid pressurizations to the high side.
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 is constructed from anodized aluminum 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 - Through years of calibrating many different manufacturers' test kits, we noticed that 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 per the ASSE 1064 verification of accuracy standards. 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, if you introduced pressure and read the gauge at 0.2 psi, the reference typically reads 0.6 to 0.7, or if you read the gauge at 0.6 it is usually 0.9 or so on the reference. 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 close to one side, often this is an indicator that the gauge may need an accuracy adjustment.
Water Proof - We added a water proof front, 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 - Aluminum ( as well as brass and plastic ) can cause deposits of calcium to accumulate on the materials, although the anodization process minimizes this for aluminum, specifically if the water is hard ( contains a lot of calcium and other minerals ) it can leave deposits and cause gauges to malfunction. In order for calcification to occur, hard water must be in non-stop contact with the components over a significant period of time. With our 2 valve arrangement, the design process has further minimized this, since it is much easier to completely drain and often does not stay water logged for very long even if left undrained since there are few places for it to settle, unless the kit is stored completely upside down with the needle valves closed.
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.
Are you taking a backflow course ? We have resale agreements with proctors and instructors of backflow courses across the USA. They often have more competitive pricing and knowledge about the local market. Most backflow schools have gauge sales and gauge calibrations available in classes, talk to your instructor about what they recommend and they often can sell test kits at the courses themselves, either the TK-2 or other manufacturers, or can point you in the right direction.
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108 First Ave, UPS Store Box #408, New York, New York 10009, United States
Email - krugerinstruments@gmail.com Phone - 917-887-5613