Is there an alternative to Dichloromethane (DCM or methylene chloride, methylene bichloride) for Low pressure flushing of PU machines?

Meth Chloride as it is commonly known within the Polyurethane Industry has been the most common flushing agent used, but that is changing! Increased environmental pressure and Health & Safety focus to find a replacement for this chemical is making companies consider what alternatives there are for Dichloromethane (DCM or methylene chloride, methylene bichloride).

Meth Chloride is tried and tested over many, many years and as such it is trusted by users for the flushing of uncured PU and elastomers. It’s a solvent that does evaporate and is therefore easily lost into the atmosphere, but this also causes significant health risks as it is a carcinogenic as well as potentially causing burns when in contact with the skin…..but as we said, it works and is proven.

Supplied in closed top barrels and used in a closed system to avoid escape into the atmosphere, Meth Chloride works by being pumped into a Low pressure machines pipes and mixer head. The Meth Chloride attacks the PU or elastomer and starts to dissolve and retard the curing and the capillary action of the liquid flowing pushes the waste PU or elastomer through the pipes.

The ideal process you would say, liquid in, curing stops, waste pushed out, any residue evaporates away and machine ready to operate again…..however that is not all the story.

I mentioned how Math Chloride is an unsophisticated solvent that evaporates, and this is good as it leaves no residue in the pipes, but it also means that a significant proportion of it’s energy is concentrated on evaporation rather than cleaning.

This means that you are relying on the capillary action to scrub the pipes and mixed heads clean through movement or friction, which may need higher pressure and more product used.

The amounts of Meth Chloride required also increases potential health & safety risk and disposal costs.

So while the costs are low for the product, the disposal costs are ever increasing.

Is there an alternative?

EN720 Non-Hazardous Flushing solvent from Bio8 Industrial is a sophisticated blend raw materials and was developed initially for a project in California. As you may be aware California is very strict about the products that can be used and this product was developed for a new pipeline being installed above ground where the consequences of a spill to contaminate the ground needed to be eliminated.

EN720 is a fully biodegradable flushing liquid which does not evaporate, therefore 100% of it’s energy is devoted to cleaning, the combination of raw materials means the liquid is what we call very searching.

What we mean by this is that it does not rely on capillary action or movement to clean, it will search out the waste stream and dissolve the uncured PU and elastomers on contact and means that 100% of the solution you have paid for is utilised!

It is also safe to handle and classified as Non-Hazardous, therefore risk assessments and employee safety is massively improved, and in today’s world of ‘blame and claim’, as well as the costs associated with a workplace injury claim and HSE fines, this then makes the product very attractive from a Health & Safety perspective.

How does it work and what changes do I need to make to my machine?

The first thing you need to do is accept that there is a change of mindset needed.

EN720 cleans very differently to Dichloromethane (DCM or methylene chloride, methylene bichloride).

With Meth Chloride you need higher pressure for a faster flow to scrub away the uncured PU residues, whereas with EN720 you want contact time!! You can slow the flush down, reducing waste and also giving the product more contact time with the uncured PU and elastomers. In fact if possible you could purge the waste from the system, then leave EN720 in the pipes for a few seconds as it is very searching and will instinctively look for, identify and destroy/dissolve any uncured PU and elastomers it has contact with.

On tests customers found that they could flush for 15 seconds with Meth Chloride, but only needed 5 seconds with EN720, and the pipes and mixer heads were much cleaner!

This means you are only using 66% less material – so immediate savings.

As it is Non Hazardous you can reuse and recycle.

But what about the costs?

Fact – More sophisticated PU flushing solutions like EN720 will never be as cheap as Dichloromethane (DCM or methylene chloride, methylene bichloride)….but you need to consider the costs not just as a straight like for like price per litre or kg.

For example

If you can use ⅓ of the solution in the flushing process you can divide the cost of EN720 by 3 to compare with Methylene Chloride

If you can re-use the solution just once you can divide the cost by 6

If you can re-use EN720 twice you can divide the cost by 9

Suddenly the option to use a Non-Hazardous Low pressure PU Flushing compound becomes more economically viable….then you work in the cost in terms of health and safety risks and disposal…..suddenly EN720 becomes much more economically viable.

Green and Non-Hazardous flushing agents for PU will never be as cheap as Meth Chloride/DCM….but they can be economical if you also consider the overall costs and risks associated with Meth Chloride from an operational perspective.

For more information regarding EN720 Non Hazardous PU Flushing Agent, click here.