Technical Updates

Continuous product control for outstanding quality

Technical Updates

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New Polypropylene Flex Gap

The patent pending Flex Gap backflow preventer (KP1H and MX versions) is now molded from polypropylene to provide greater compatibility with the variety of corrosive chemistry used in the institutional/commercial cleaning industries.

To further improve the reliability of the Flex Gap, we have replaced the silicone sleeve with a new EPDM sleeve that has been verified to last longer and reduce the likelihood of ruptures and splitting. A horizontal rib placed across the air gap has been added for strength.

The new Polypropylene Flex Gaps will begin shipping in March. If you have any questions or concerns, please talk to your Knight representative.

Micro-Pro II Enhancement

The Micro-Pro II circuit board has recently been modified to accommodate a two-transformer configuration. This option allows the already-versatile

MP-II to serve an even wider variety of applications. The use of dual transformers is geared for particular machines, such as Hobart’s popular AM-14, and ensures that power to the dispenser will be "off" when the dishmachine is not in use.

When using dual transformers, the board’s signal inputs are not required -- the transformers act as the signal inputs. Shunt jumpers have been added on the right center of the control board for selecting the desired configuration:

  • JP1 & JP2 for dual transformers
  • JP3 & JP4 for single transformer

On-Premise Signal Lockout Feature

The On-Premise, On-Premise Plus, and Multi-Flow, all have a feature that is called Signal Lockout. Signal Lockout can be used to prevent multiple product injections when a supply signal is received several times during a wash cycle. When using the "fill" solenoid as a trigger signal, a solenoid may energize due to low water level in the washer.

The lockout time is selectable and starts counting down when a pump stops running. Any signals received for a pump that has performed its function in that formula will be ignored during the count down period. Any lockout time that may still be counting down when the load count pump activates will be terminated in preparation for the next formula.

The On-Premise lockout time can be selected from 0 to 255 seconds, the On-Premise Plus can be set from 0 to 75 minutes, and the Multi-Flow lockout time is selectable from 0 to 99 minutes.

The Knight-Trak II has a 5 minute lockout that you can enable or disable. If you still receive multiple injection signals, you can set delay times with no volumes on the second and third levels of your formula.

WinReporter Com Port Usage

All WinReporter software programs require a special hardware key cable to be plugged into a working com port on your PC. This cable is included with the software package, and while it may look like a plain old cable, is actually a proprietary Knight component.

WinReporter software is designed to automatically detect the presence of this cable. If you see a message stating, "This program requires the Knight Reporter cable", it indicates that the special hardware key cable was not detected on your computer.

First check the basics, such as…Are you using the cable Knight provided in the software package? Is the cable firmly plugged into the PC? Are there any bent, or missing pins on your PC’s com port? Are there any programs running in the background that also use the com port (i.e. Palm Pilot interface)?

Other factors that can interfere are usually more complex and/or related to the PC itself. Examples of this would be com port addressing and IRQ conflicts, just to name a few. Fortunately, these factors don’t occur very often. If you are unsure that your PC has a com port, or if your com port is working correctly, please contact your PC vendor for assistance.

Squeeze tube length increased on On Premise and On Premise Plus

The T-50E squeeze tubes for the On Premise (OP) and On Premise Plus (OPP) have been lengthened from 11 inches to 14 inches (7019060). The longer squeeze tubes will make it easier to connect the pumps to the checkvalves on the On Premise Plus Flush Manifolds.

Pump Calibrating Procedures For Flush Manifolds

When calibrating a peristaltic pump, chemical is dispensed from the discharge side of the pump into a beaker or other measuring container at the point of injection. To properly calibrate a peristaltic pump that injects into a flush manifold through a checkvalve and into dynamic water pressure, another method must be used.

For greatest accuracy, the correct calibration method is to measure at the suction side of the pump. By drawing chemical out of a beaker or other measuring container and noting the liquid level before and after the pump runs, you can easily determine the amount of chemical dispensed.

Another benefit of this calibration method is that it’s quicker and easier. You don’t need to disconnect the squeeze tube from the manifold to get a calibration…that’s a real time saver!

The following diagram is an example of using the suction side of the pump to draw chemical out of a graduated cylinder. Do not remove the suction tubing from the pump. An accurate calibration requires that all tubes, which constitute friction loss and head pressure, be in place.

New Multi-Flow Features

Knight’s new Multi-Flow System offers some great features that increase system reliability and ease-of-use for the installer and the operator. The features are:

  • New Cable Configuration For the Remote Control
  • Auto Formula Select (AFS) with Adjustable AFS Signal Time
  • System Lockout

New Cable Configuration

The new Multi-Flow cable configuration provides a male to female extension cable that allows the remote to be removed and reconnected to the female pigtail at the dispenser. This change enables hassle free priming and programming of the system at the dispenser cabinet without the need for special male x male pigtail cables.



Auto Formula Select

The Auto Formula Select feature will eliminate potential mistakes by the person operating the

This feature allows the laundry machine to send a signal to the Multi-Flow dispenser, which automatically selects the correct wash formula. The "AFS" signal time is adjustable to designate a time "increment" for selecting formulas. The time increments can be set at 1, 2, or 5 seconds. For example, if the AFS signal time is set for 2, a 20 second signal from the washer would choose formula 10.

System Lockout

The System Lockout feature will "lock-out" all incoming supply signals for a period of time after the load count pump receives a “load count” signal. This will eliminate false signals and signal errors and ensures correct chemical distribution. The lock-out time can be set between 0 to 99 minutes.

Troubleshooting probe style warewash dispensers

Probe style dispensers monitor the detergent concentration level in dish machine wash tanks. Two settings determine the accuracy of the detergent control, the probe and the concentration.

Common technical questions for probe style warewash dispensers are:

  • Detergent feeds continuously,
  • Detergent pump (or solenoid) does not feed.



1: Check probe wiring connections at the circuit board and at the probe.
2: Perform a "Short Test". The detergent feed should stop when the following connections are "shorted".

Step A: Check the probe terminals at the circuit board. Take a piece of wire and short across the two screws where the probe is wired.

  • Results: Feed should stop. If the detergent feed does not stop, the circuit board may be bad.
  • Solution: Replace the board and reset the concentration.

Step B: Short the probe wire connections at the probe.

  • Results: Feed should stop. If the detergent feed does not stop, the probe wire may be bad.
  • Solution: Replace the wire.

Step C: Short the probe tips on the probe.

  • Results: Feed should stop. If the detergent feed does not stop, the probe may be bad.
  • Solution: Replace the probe.

If the detergent feed stops at each step then the problem could be hard water, high temperatures, or continuous fresh water fill diluting the chemical strength.


1: Check pump or solenoid wiring connections.
2: Disconnect one of the probe wires. This should start the detergent feed at the detergent feed cycle.

Step A: Start at the circuit board and disconnect one of the probe wires.

  • Results: Feed should start. If the detergent feed does not start, the circuit board may be bad.
  • Solution: Replace the circuit board.

Step B: Disconnect one of the probe wires at the probe.

  • Results: Feed should start. If the detergent feed does not start, the probe wire may be bad.
  • Solution: Replace the cable

Step C: If the detergent feed starts at each of the step above, the probe may be bad. Replace the probe.

If the problem persists, it could indicate a "floating" ground in the dish machine. Make sure the probe is mounted below the water line near the recirculating pump intake, and 3-4 inches from the corners, heating elements or bottom of tank.

Squeeze Tube Compatibility

The most critical component of a peristaltic pump is the squeeze tube. While it may look like a simple "rubber hose" it performs the rugged task of repeated compression and expansion to move liquid through it. A squeeze tube must perform this task very consistently to provide accurate flow rates and long term reliability. Knight squeeze tubes are custom made of proprietary materials with a strong focus on inside/outside diameter tolerances. Our attention to quality by checking every squeeze tube ensures a correct fit and consistent operation for new systems, or for tube replacements.

Under normal operation, a squeeze tube will typically last about 6 months. If a chemical aggressively attacks the tube, it will cause the tube to either harden or turn spongy, which greatly reduces its usable life. To meet the diverse needs of the chemical industry, we offer squeeze tubes made from a variety of elastomers. The table below provides general compatibility guidelines for the different types of squeeze tubes available from Knight. The "type" column refers to the suffix letter of the tube model.

Examples: T-50-E T-66-M T-86-T

The following table is provided for identification of the five most popular squeeze tube sizes used in Knight pumps. The measurements shown are the closest fractional value (inches) for reference.

Fixed Pressure Regulator

Have you experienced a problem with excessive foaming when filling spray bottles or mop buckets? The root of the problem is usually water pressure in excess of 60 PSI (Dynamic). Knight recomments that you install a low cost fixed pressure regulator to control the water pressure at a maximum of 40 - 50 PSI. High water pressures can also vary the ratios and flow rates of the proportioner; so installing the fixed pressure regulator is key for optimum proportioner performance.

Knight’s fixed pressure regulator is 3/4 MNPT x 3/4 FGHT, which provides a quick and easy installation. Below is an example of a typcial installation:

The Knight part number for the fixed pressure regulator is 7407117. We recommend keeping a few in stock for high pressure installations.

On-Premise Plus Drain Mode

One of the new features recently added to the On-Premise Plus laundry system is "Drain Mode" operation. Drain Mode maximizes the versatility of the dispenser by providing a simple and reliable signal interface to washers that do not have typical supply signal connections, or where the washer’s supply signals are not operating correctly. This feature only affects how the pumps are triggered – all other functions such as pump run times, delay times, and flush mode, will still operate in their normal fashion.

Drain Mode requires only one signal source from the washer and works by counting the number of drains during a wash cycle. When programming the OPP dispenser for Drain Mode, each chemical pump is assigned a specific drain occurrence to inject product on. The washer’s drain mechanism will typically energize the solenoid to close the drain and de-energized to open the drain. This type of drain activation is standard on almost every Wascomat, Milnor and Uni-Mac washer, however Drain Mode can be set to recognize an "inverted" signal (one that energizes to open the drain) if necessary.

Another new feature recently added is "Formula Enable" which allows you to choose only those formula numbers that you want visible to the operator for selecting the chemical formula from the On-Premise Plus remote control. This makes the remote control more user-friendly to the operators, and eliminates the chance of missed chemical injections due to inadvertently choosing an unused formula.

Refer to the On-Premise Plus instruction manual for specific details on setting up and using these exceptional new features.

New On-Premise Checkvalve Improves Performance

The On-Premise flush manifold was recently modified in several ways to improve performace. The most important change is a new style checkvalve. The new checkvalve features a ball check with Hastiloy spring and Viton O-ring. For some laundry chemistry, the new checkvalve will improve service life over the previous "sleeve" design.

Old style OP manifolds can be retrofitted with the new checkvalve, however this is only recommended for up to 4 pumps, as the 5th port on the old manifold block faces the rear of the unit and does not allow enough space. To retrofit an old style OP manifold with the new checkvalve, you will need to change the T-50-E pump squeeze tubes to the 14" length (P/N 7019060). The additional tube length will allow the squeeze tube to connect to the new checkvalve (P/N 7901234) without any kinks. See photos on the back of this Technical Update for installation example. As always, don’t hesitate to call Technical Services with any questions.

Retrofitting an old style On-Premise manifold with the new checkvalve? Here’s an installation example.

Main power connection for Micro Pro and Ultra Micro Warewash Dispensers

Will you be installing a Micro Pro unit soon? If so, remember the "MP" and "UMP" require 3 separate power connections for “probe” operation.

  • Main or constant power
  • Rinse signal power
  • Detergent signal power


One set of connections for a “probeless” door machine. In this bullitin we will look at probe installations only.

The purpose of the "Main" power connection is to provide power to the unit. The "MP" and "UMP" are built with one step-down transformer for the "Main" or "Constant" power connection. The transformer will accept a 115/208/220 volt power source. Connect the transformer to a power source that is "on" constantly, or when the dishmachine is "on".

For Example: You are installing to a Hobart C-44 machine. You ask, what electrical contacts do I use to connect the dispenser properly? The popular C-44 is a conveyor machine with a control box that contains a magnetic contactor switch for the recirculating pump. Inside you’ll find terminals marked T1 and T3 for the recirculating pump that are "hot" when the machine is turned "on" and "dead" when the machine is "off". Connect the Main Power transformer to these two terminals. The C-44 provides "DPS" and "RPS" terminals for chemical dispenser signals. Connect the detergent signal to DPS and the rinse signal to the RPS terminals.

Other common contacts on dishmachines to connect for constant power are the following:

  • L1 and L2 contacts (main power contacts for dishmachine)
  • Main switch on dishmachine
  • Wall outlet