Model 855

5 Valve Digital Backflow Test Kit

Introducing the Future of Backflow Testing: The Digital Backflow Testing Device!

Say goodbye to manual paperwork and hello to efficiency and accuracy with our revolutionary Digital Backflow Test Kit!

Precision at Your Fingertips: Our device utilizes state-of-the-art digital technology to ensure precise and reliable backflow testing results every time.

Streamlined Workflow: With intuitive digital interfaces and automated data logging, our device simplifies the entire testing process from start to finish. Spend less time on paperwork and more time serving your customers.

Comprehensive Reporting: Generate detailed reports instantly, complete with digital signatures.

Built to Last: Crafted from proven materials and backed by our commitment to quality, the model 855 Digital Backflow Test Kit is built to withstand the rigors of daily use, ensuring long-lasting performance and reliability.

Functions and Applications:
The model 855 kit provides the capability for testing all brands of reduced pressure principle, pressure vacuum breaker and double check valve backflow prevention assemblies.

∆P Range: 0-15 PSID, Pressure sensor 0-200 PSIG

Basic Features:   (Included with activation)

  • Read ΔP and line pressure digitally on your phone.
  • Record test values with capture buttons or toggle switches.
  • Test fields change based on the assembly type selected.
  • Special program for capturing PVB air inlet opening point.
  • Saves all tests results to the cloud.
  • App works on Wi-Fi, Cellular, or Offline when no signal.
  • Sort, filter and search saved test results.

Premium Features:   (Requires subscription after 30 days)

  • Autofill customer & assembly information by searching previously tested assemblies.
  • Download the day’s test data into a .csv spreadsheet for easy review or upload the completed tests to another program.
  • Generate PDFs to save, share, or e-mail.

Want to see the machbackflow app in action?    Watch this video:     App Overview Video

  • Model 855 requires activation of the Machbackflow app on your IOS or Android device.   
  • Basic app features included for the life of the kit.
  • Premium features included for first 30 days after activation.   
  • Annual subscription to Premium  app can be purchased from:
  • Mobile device not included with purchase of test kit 
  • Lead time is 7-10 business days after receipt of order confirmation.


Product Features/Benefits

  • Advanced Digital Technology: Enjoy all the functionality and accessories of the popular Model 845, enhanced with cutting-edge digital features for improved performance and efficiency.
  • Seamless Mobile Integration: Utilize Bluetooth connectivity to sync with your mobile device, allowing you to view test data directly on the user-friendly Machbackflow iOS or Android App.
  • Effortless Data Management: Build and maintain a comprehensive database of customers and assemblies with the Machbackflow app, ensuring easy access to previous tests, repairs, and other vital data whenever you need it.
  • Tailored for Backflow Prevention Testing: Specifically designed to meet the unique requirements of testing backflow prevention assemblies, providing reliable and accurate results every time.
  • Consistent Testing Standards: Utilize the same case, hoses, and fittings as the Model 845 analog test kit, ensuring consistency and familiarity for users transitioning to digital technology.
  • Easy to use: Identical valve configuration to the industry leading model 845-5 test kit.
  • Convenient Storage and Portability: Carry and organize your test kit with ease using the durable molded plastic carrying case, complete with integrated storage compartments for fittings and tools. The portable unit is removable from the case, featuring a removable strap and cell phone holder for optimal accessibility during tests.
  • Enhanced Durability and Performance: Equipped with 90-micron filters to minimize plugging from scale, sand, and other debris, ensuring reliable performance even in challenging conditions. Filter elements can be easily cleaned or replaced as needed.
  • Basic App Access: Machbackflow app activation and lifetime access to the apps basic features is included for the life of the test kit. ($350 value - Included in sales price)
  • Premium App Access: Enjoy one month of trial subscription to premium app features upon activation, enhancing your testing experience with additional functionalities.
  • Long-Term Reliability: Rest assured with a comprehensive 5-year warranty, providing peace of mind and ensuring continued support for your investment.


  • Gauge Type Capacitive Differential Pressure Sensor
  • Differential Pressure Accuracy ± .2 P.S.I.D.
  • Working Pressure: 200 PSIG
  • Body Material: Glass Reinforced Engineering Thermoplastic
  • Wetted Internals: EP Elastomers, Brass and 316 S.S. Metal Parts
  • Piezoresistive Line Pressure Sensor 0-200 PSIG
  • Rechargeable Lithium Ion Battery
  • Soft-Seated Brass Needle Valves (with replaceable valve seats)
  • Hoses with Inline Filters & Schrader ¼” brass coupler End Fittings
  • Hose Length: Three (3) each / 5' long (color-coded)
  • Bleed Tube, One each / 4' long clear bleed tube.
  • Adaptor Fittings: (3) sets of brass fittings provided for hookup to all standard size test cocks
  • Gauge Weight: 3.6lbs / 1.6kg
  • Case: Durable Molded Plastic
  • Size: 18 1/2"L x 9"W x 9 3/4"H
  • Temperature Limitations: Maximum 150°F/65°C


It is capable of performing all known test procedures including those recommended by ASSE, AWWA, CSA, FCCC and HR-USC and NEWWA.

The Mid-West Advantage


Being a tester now going on close to 20 years when your given the opportunity to try a new backflow gauge I’m not going to lie you kind of turn up your nose a little bit. Why try something different than the tried and true Midwest 845-5. I mean that’s how I was ten years ago when I had my first interaction with an old antiquated digital kit that printed out the results. While that test kit was cool that it printed out the results and I didn’t have to remember things, it was heavy, took batteries, and well didn’t like the water very much. Fast forward 8 years to another digital kit and well I still had to move results saved from the unit to paper forms and well it just didn’t have that feel in your hands as an 845-5.

So then along comes the new Midwest 855, the first time I took it out of the box I was a little taken back by the no dial and well no screen. But let me tell you when I put it in my hand I felt right at home and there was no big weight difference. So being that I help manage a company with 8 full time backflow testers and some plumbers where we test over 20,000 backflow assemblies a year let me tell you I’ve been hesitant to put some of the current electronic gauges in my tester’s hands. Simply put new testers have a tendency to overtighten control and blead valves on the gauges and the 845 has always just been nice for us to be able to take care of those small maintenance of the gauge throughout the year by replacing worn needle valve seats and control valves as needed instead of sending them into a shop to get repaired. So, after working with this gauge for some time now well my feeling has changed a little bit, I mean at least with the moving some of my guys to the 855 only because really the only thing that has changed with the 855 vs the 845 is no more analog dial but the manifold and control valves are exactly the same.

There’s an App for that! Yep, that’s right you get to use your phone to get your readings. Really, it’s not that bad you Bluetooth to the gauge and then once you either find the assembly (prepopulated off of your data) or enter in the new assembly info all you have to do is tap your phone to record your reading to what your testing weather that check 1, rv opening, ect…. Takes a little getting used to but it’s not a big learning curve.

Overall, for moving into the new digital world of gauges I’m all for it. Now the only thing it’s missing is integration into the many worlds of online test report entry…

Kyle Harms Vice President American Backflow & Plumbing Services Oregon & Washington

Let me start off by saying Wow!

Wow this test kit has made my life as a tester easier, faster, and more efficient.

While it should be no surprise that this kits fit and finish would be great, I’ll say it anyway, its great! I love my 845, 5 valve analog kit and you may think, there will always be a place for analog kits, and you may be right. However, theres no denying that the world is moving towards all things digital and the 855 has met that need very well. First off, holds well, with a good fit in your hand while testing. Not a heavy or bulky kit at all which is a plus for me testing all day. There’s barely a learning curve at all and I’d even argue its ease of use could actually aid in teaching backflow testing to new testers. As much as I love my 845, (did I say that already?) the benefits of going digital with the 855 has sped me up and made the back end, paperwork side of testing, a breeze to get through. No more “where did I put my pen?” and no more wet papers being filled out in the field. I cruise through my data collection using the speak-to-text on my phone to call out make, model and serial numbers as well as any other pertinent info, then I’m on to testing faster than I had ever been before. Repeat tests or coming back to test again after repairs goes even quicker. I’m adapting with the times and have gone digital and I’m not looking back. I’m stoked I chose the Midwest Instrument 855!

Joel Fabricius Flowrite Backflow Inc South Florida, on the Treasure Coast

Testimonial from our tech:

The software/app for this device is very user friendly. When entering a new site into the software that is not uploaded prior to arrival, it is easy to enter the site’s info and multiple device’s testing, since the site info auto fills after saving the previous test info. Exporting the test information to the office via email is a really neat feature and limits time in the field. Found the gauge was accurate to our regular test gauge and easy to read digital readings if you needed to go back in and find readings on previous testing.

Notes from the office:

Obtaining test info from the field via email is a super cool feature. We believe that this software and mobile ability will greatly reduce the overhead in the office due to paperwork processing being exported from the field and imported to the office’s software. We look forward to potential future upgrades-perhaps we can submit reports to the cities upload sites in the future.

They generate test reports in the app and email them back to the office they have brought up several times to me how much more efficient that is then waiting to bring back a stack of test reports from the field.

Taylor Plumbings