Belimed Washer / Disinfectors: Detergent Dosing System

An important part of any automated washer is its detergent dosing system. The reliable performance of this system is critical to the cleaning and disinfection process performed by the washer. This not only keeps surgical instruments clean but also increases their overall lifespan. Failure to dose properly can cause cycle failures and improperly cleaned instruments.

How does it work?

The standard design for a Belimed washer includes three integrated dosing pumps (1 - 3) with the option of adding two more (4, 5) for a maximum of five dosing pumps. The pumps are located below the chamber behind the servicing front panel. Typically, dosing pump #1 is used for detergent and dosing pump #3 is used for instrument lubricant. Dosing pump #2 is not typically used.

The dosing pumps are a type of peristaltic pump. Peristaltic pumps use a roller and squeeze tube to pump liquid through a flexible tube. As the roller rotates, the squeeze tube is compressed causing a pumping action pushing liquid through the tube and into the washer.

See the table below for a typical washer detergent setup:

Each dosing pump is connected to a flowmeter and suction lance. The suction lance allows for detergent to be pulled from the detergent container and into the dosing supply line. It is critical that the end of suction lance always be completely submerged in the detergent supply. Failure to do so could allow air to enter the dosing system causing dosing errors, something we see commonly occur.

Flowmeters ensure that the correct amount of chemical is used for each part of the cleaning process. These devices spin as liquid flows past them calculating the precise amount of chemical being dosed into the washer. When it comes to dosing precision the following is important to remember:

Using too little detergent will result in loads not being cleaned properly.
Using too much detergent will result in foaming inside of the washer. Foaming negatively effects the washer’s performance and can cause cycle failures. Excessive detergent use can also impact the lifespan of surgical instruments.

Flowmeters should be checked annually for proper adjustment. In addition to the annual check, flowmeters should also be adjusted if any portion of the machine’s dosing system has changed. Examples of changes that can impact flowmeter adjustment are:

Changes in the distance between the dosing container and the washer.
The type or brand of detergent has changed.
A dosing pump or flowmeter has been replaced.

Key Take-Aways:

Promptly replace detergent containers when they are low/empty. This reduces the chances of air getting sucked into the dosing system. When changing containers, always hold the detergent suction lance vertically to help prevent air from entering the dosing system.
Never place the detergent suction lance on the floor. This increases the likelihood of air entering the system and can allow contaminants to enter the detergent container.
Too much foam will cause a cycle error. Ensure instruments are properly rinsed before placing them inside the washer. Pretreatment or other chemical products will carry over into the wash cycle and cause excessive foam formation.
Flowmeters should be checked for proper adjustment at least annually and readjusted if a change has been made to the dosing system.