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Dilution-control systems

September 19, 2010
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From manufacturers to building service contractors (BSCs) to end users, the cleaning industry deals with several components every day as part of the products and services it provides.

The basics include chemistry, equipment, packaging and the service model.

While chemicals can be purchased in ready-to-use form, more and more professional cleaning managers are finding out that dilution-control systems are one of the best ways to control costs and ensure safety.

Ready-to-use products provide peace of mind that cleaning workers have access to the right chemicals, at the right concentration.

Crucial to dilution control is maintenance of the system. It is important to ensure systems are working properly to deliver the correct dilution.

Preventive maintenance is preferred, as anything “emergency” or “unscheduled” can take resources (money and time) away from the cleaning task at hand.

Consider system types
There are two types of dilution-control technologies available today that are the basis for all systems: Eductor and gravity feed.

Eductor systems are a “venturi type” system that uses negative pressure created by flowing water to “suck” chemical through a small hole.

The hole diameter is set to deliver the right chemical dilution.

The dilution tips are either manually inserted in the equipment or permanently installed in the chemical packaging.

Gravity systems rely on Mother Nature to drop chemical into a mixing chamber that is flooded with water.

Systems using gravity have various proprietary methods to get the correct dilution.

Most of these systems use technology installed in the packaging to control the dilution.

Understanding the ins and outs
There are pros and cons to both eductor and gravity-feed systems, but there are only pros when it comes to preventive maintenance requirements that should complement each system to ensure optimal performance.

Eductor systems are susceptible to water hardness.

White buildup around the bathtub drain and spotty glasses in the dishwasher are both results of hard-water use.

This scale buildup can affect performance, safety and costs of dilution-control systems.

The build-up also can alter the dilution by as much as 50 percent.

The best-performing dilution systems control within plus or minus 10 percent.

Scale buildup can occur on the two types of eductors used to prevent the backflow of chemical into the water source, which can also alter the chemical levels.

The first type of eductor used to prevent the backflow of chemical is an airgap that uses an actual gap in the water flow to ensure the water can’t go back into the source.

It would be as if you took a garden hose and cut a one-inch section out of the middle and lined up the hose so the water kept flowing from one section to the other.

Airgaps are susceptible to water hardness at the point where the water flows through the safety gap (the cut section of the garden hose) or where the dilution tip mixes the undiluted chemical in the water flow.

As build-up of scale occurs, the water will start to spray inside the piece of equipment (much like what happens when you stick your finger into the gap in the garden hose) and the tip will start to clog, changing the diameter of the tip opening.

The result will be a reduction in concentration of the diluted chemical.

It is very important that any system using airgap eductors and/or dilution tips is checked routinely for tip clogging and scale build-up.

However, when checking and cleaning the tips, special care is required because the diameter of the hole in the tip can become altered (if the service person uses a small piece of wire to unclog the opening).

The alteration in diameter would then increase the concentration of the chemistry and affect the use, cost, effectiveness and safety of the end product.

Separation is key
To prevent this problem, several systems are available that separate the eductor and the tips by putting the tips in the packaging.

The separation eliminates the potential for the tips to change diameter as the tips are never in contact with water and are also replaced every time the user replenishes the chemical.

There are also dilution systems that use a peg rather than a tip to dilute the chemical by having the chemical flow around the peg for dilution, rather than through a hole.

An advantage of the peg is that with preventive maintenance, the service person can wipe the outside of the peg regularly and not have to worry about changing the dilution of the chemical.

An acid-based cleaner works well in removing scale buildup.

The second type of eductor is a “sleeve” that allows water to flow toward the chemical but will not allow the chemical to backflow to the source.

The “sleeve” technology, not approved in certain areas, prevents water from spraying inside the equipment by flexing the sleeve every time the eductor is used, essentially cleaning it.

Sleeve systems should also be checked for scale buildup if the tip is not installed in the packaging.

The systems that use gravity to dilute chemistry have preventive maintenance requirements similar to the airgap systems.

Water hardness may build up where the water flows into the mixing chamber.

Most of these systems, however, will have dilution tips that come in the packaging and are replaced when the chemical is used up, never having to interface with the flowing water.

There are products available in portable dilution-control systems that combine the chemical, packaging and equipment, eliminating the need for preventative maintenance.

Combining an eductor for bottle/bucket/sprayer applications, a dilution tip and water connection into the actual chemical packaging these “ready to dispense” systems ensure that the user maintains cost control, safety and dilution without having to worry about preventive maintenance or any emergency service.

The benefit of this system is that when the packaging is empty the complete system is sent to the recycler and a completely new system is pulled out of the box for use.

Additional line of defense
All of these systems must have clean water flowing into them, so it is a good idea to put some sort of filter in the water line before it is combined with any type of dilution-control system.

A simple strainer works well and should be checked during a preventive maintenance visit.

If the dilution-control system is hooked up in a location where there is a water diverter, there are some strainer/filters available that can filter the water going to the system and then self-clean when the water is diverted into the sink.

Dilution-control preventive maintenance is extremely important today when cost savings, worker safety, and product effectiveness are high priorities.

Cleaning managers and professionals should take the time to support their chosen systems (chemical, packaging, equipment and service model) with a very simple preventive maintenance schedule.

The results will be satisfied managers and safe workers and customers.

David Collette is platform manager for dilution control, and Van Walter is customer technical support manager for JohnsonDiversey North America. They can be reached at
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