Intermediate cooling medium for second circuit – 10 questions answered

July, 2014

Imagine a large-scale enterprise or hypermarket equipped with a refrigeration supply system having a second cooling circuit... At some stage you will have to decide which cooling medium you will fill your system with.
How to make a good choice? What agent to select? Which parameters should be taken into account?

Professionals of «STRON» LLC, a cooling (heat) media manufacturing company, will answer all that questions.

Basing on the experience of answering the questions we get every day from the heads of enterprises and their engineers while choosing a cooling medium, we will tell about main factors you should consider and key questions being received. We will build our answers with account of propylene glycol cooling media because of production specifics and branch development tendencies.

Question No. 1.

Ethylene glycol or propylene glycol?

We (as well as the rest of civilized world) choose propylene glycol. Ethylene glycol and propylene glycol are considered to be related but ethylene glycol is poisonous and toxic, that is why it is strictly not recommended for usage at food enterprises. The only possible option is to exclude any contacts of ethylene glycol and its evaporations with products and humans. Propylene glycol is a nutritional supplement, so cooling media based on it are environmentally safe.

Further we will give answers on questions regarding propylene glycol fluids.

Question No. 2.

Can I fill a system with pure propylene glycol and what temperature it freezes at?

Pure propylene glycol does not freeze the same way as ethylene glycol creating clear ice crystals. But under slightest negative temperatures it becomes absolutely still like a jelly. No pump can move a substance of such consistence and no circulation can be done. Water mixes of propylene glycol are used as cooling media, they retain operational properties at low temperatures.

Question No. 3.

How to mix propylene glycol?

You should not do this if you have no experience in. Everyone has to mind its own business. Proper concentration has to be selected, special treated water has to be used, ultimately even mixing has to be reached, the final result has to be controlled... You should seek help at a cooling media manufacturing enterprise.

Question No. 4.

Which temperatures a cooling medium should be operated at?

It depends on temperature modes of your system.

Maximum possible temperature is usually conditioned by heating of the system. Propylene glycol cooling media usually boil at the temperature exceeding one hundred degrees, this is quite sufficient.

Minimal possible temperature determined either by the cooling process or by location of equipment in unheated premises or open site. In the second case you should take into account the lowest temperature, for our climatic zone you may consider −300С, for example, having in mind the winter of 2005-2006. In order to ensure system operation at any time a cooling media should freeze at the temperature that is lower than the possible one by 2-3 or 5 degrees.

Question No. 5.

Will propylene glycol mix corrode the system materials?

Yes, it will. Even water is a corrosion active substance. In order to reduce cooling medium effect on ferrous and non-ferrous metals and system gaskets the mix has to contain corrosion inhibitors. We recommend to buy a full-pack cooling medium with additives, not just a solution. Except peace in your mind you will get the certificate of quality with specified fact of conducted tests by anticorrosion indexes.

Question No. 6.

Do you need to colour a cooling medium?

On the one hand, cooling media used in engineering communications are often coloured in order to mark technical designation of liquid. Sometimes the liquid can be coloured with bright or fluorescent dyes to simplify the location of a leakage source (by visual inspection or in ultraviolet light). On the other hand, majority of food enterprises often orders uncoloured cooling media.

Question No. 7.

Can I mix a cooling medium by myself?

In fact, you can. But we do not recommend you to do that. Firstly, you have to use right-treated water and in right proportions. Secondly, the amount of anticorrosion additives will be reduced in uncontrolled way when mixing. Thirdly, a cooling medium manufacturing enterprise will not bear any responsibility for the product you modified on your own. In case any problems arise you will have to resolve them all alone. You should take all these factors into account in case you want to save some money on transportation or when you discover that you lack amount of bought cooling medium when filling a system with it.

Question No. 8.

Can I fill up the system that already contains a propylene glycol cooling medium made by one manufacturer with a propylene glycol cooling medium made by another one?

Propylene glycol made by different manufacturers is fully compatible with each other. Although, there is another danger: additives contained in the first cooling medium can conflict with additives contained in another cooling medium. Additive composition is commercial secret of the manufacturer, so do not even try to ask it from personnel of the enterprise. If you decide to experiment and mix two different samples, you cannot know what is really going to happen to your equipment. We strongly recommend you not to mix cooling media of different manufacturers. In any case you will do that at your own risk.

Question No. 9.

How long a cooling medium can be used?

Propylene glycol cooling media have sufficiently long operational lifeUsually, operational life is not less than 5 years. But often it can be used even after ending of warranty period. In this case you have to test cooling medium parameters. It is better to apply the request to the manufacturer of a cooling medium. In any case, the laboratory conducting checkout test has to be accredited to execute works for this type of products. Only professionals can conduct tests correctly and explain you obtained results in a practical way. Besides after receiving of the results you will need some help in deciding what to do with your cooling medium.

Question No. 10.

Is it allowed to use a purchased cooling medium at a food enterprise and where is that designated?

The scope of usage of a cooling/heat medium is designated on the first page of specifications according to which it was manufactured. A cooling medium should be followed with the Safety and Health Certificate of the Ministry of Health of Ukraine that allows its usage it in the food industry. It is another benefit in purchasing of a ready cooling medium with a full document package.

This article outlined the key questions arising when resolving the task of selection of an intermediate cooling medium. Obviously, the list of questions is not full and changes depending on particularity of a specidic task and enterprise. Sometimes you have to implement unconventional solutions, approaches, methods. You will get significantly close to the successful solution of your task having the professionals preliminary revealed all details of it. You should trust completion of the job to the team of qualified professionals to get an optimal result you need. And do not forget that collaboration will not end after this. You can receive further support: continuous monitoring, additional product deliveries, additional services and consultation.

Make a right choice!