Telephone: +44 (0) 20 8281 6370

Telephone: +44 (0) 20 8281 6370

Critical Cleaning Solvent

Guide to critical cleaning of oxygen components

The COVID pandemic of 2020-2023 increased the demand for critical cleaning of oxygen components to treat patients with symptoms. The need for respirators and installation of new and extended oxygen systems in hospitals, clinics and care homes with the provision of ancillary pressure reduction and delivery systems led to a massive increase in demand for the valves, fittings and pipelines which control the supplies from storage tanks and cylinders, all of which needed critical cleaning.


Cleaning for oxygen service is best defined as the removal of combustible contaminants from the surface of any equipment or system in oxygen service. Essentially, any component that may encounter an oxygen rich environment.

The combustible contaminants include organic and inorganic substances such as hydrocarbon material for example oils and greases, paper, fibre, dust, and soils. If these contaminants are not removed properly, in a worst-case scenario, this can cause combustion or explosion in an oxygen atmosphere or at the least rejection of the product due to unacceptable product purity.

Oxygen is not flammable, but it supports combustion. Oxygen can react with most materials. The higher the oxygen content and/or pressure in a system the more vigorous the combustion and the lower the ignition temperature required. Materials that do not normally ignite in air will burn and may explode in an oxygen rich environment. In addition, the oxygen rich environment will give rise to a higher flame temperatures and combustion velocity with potentially devastating consequences.

The recognition of oxygen’s reactivity has led to stringent requirements regarding the cleanliness of equipment in oxygen service. Strict guidelines exist to ensure that care must be taken in the selection of equipment including all materials and components, which all need to be oxygen compatible. They must also be free from combustible contaminants as described above.

Special consideration must be given to any cleaning processes employed in the manufacture and maintenance of all components of oxygen service systems. There are many options depending on the type of contaminants from aqueous to semi aqueous and blasting systems to remove welding slag etc. These are all referenced in the publications in the addendum below and we refer particularly in this article to the European Industrial Gases Assn (EIGA) DOC 32 Solvent Cleaning.

Solvent cleaning offers huge benefits in cleaning processes. ProSolv 5408e  is especially relevant for this use. Energy saving, totally recyclable, environment friendly zero ODP and GWP and safe for operators. High output, very fast process times, non-flammable, an excellent solvent for all the oils, greases and other organics which need to be removed after manufacturing processes and it is compatible with all types of metals and equipment, from immersion cleaning in simple multi tank counter current processes to integrated vapour and vapour liquid tanks with and without ultrasonics. EnviroTech Europe have extensive partnerships with equipment manufacturers through our distributors worldwide and information and advice on solvents and solvent systems and which need to be considered Some of these are discussed below.

Specific consideration must be given to the following:

  • Cleaning standard to be achieved (how clean is clean?)
  • Cleaning procedure
  • Solvent cleaner to be used
  • Surface properties of the parts to be cleaned
  • Shape and geometry of the material
  • Types and amounts of contaminants
  • The degree of automation required

The size and capacity of the equipment is determined by:

  • The size of the material or components to be cleaned.
  • The required throughput.

Your starting point should be the cleaning standard and procedure. Solvent cleaning and solvent vapour phase cleaning of components consists of the removal of contaminants by immersion in the solvent, possibly with the addition of ultrasonic agitation and the action of continued condensation of solvent vapour on the component surfaces. The procedure requires that the oxygen equipment, system or component is colder than the solvent boiling point. This allows the vapour to condense on the components and perform a final rinse.

The major significant advantage of solvent cleaning is that vapourised solvent is always pure, and the contaminants remain in the boiling liquid section which requires only periodic cleaning out, thus causing a reduction in the frequency of system downtime.

The effectiveness of a particular cleaning agent depends upon the method by which it is used, the nature and type of the contaminants and the characteristics of the article being cleaned, such as size, shape, and material. Final evaluation of the cleaning agent should include testing of actual products and production processes.

All equipment must, together with the cleaning chemistry, comply as a minimum with current legislation for health, safety and environment. The efficiency is controlled by utilising typical samples, written procedures and requested criteria for cleanliness.


As part of the programme of worldwide harmonisation of industry standards, the European Industrial Gases Association, (EIGA) has published EIGA Doc 33-18, Cleaning of Equipment for Oxygen Service. The publication was developed from the Compressed Gas Association Document G-4.1 Cleaning Equipment for Oxygen Service and the EIGA Document, Doc 33 Cleaning of Equipment for Oxygen Service.  For information see EIGA’s website.



Sustainable vapour degreasing solvent blend from EnviroTech Europe ticks all the boxes and has the perfect profile for critical cleaning.

ProSolv 5408e has a unique range of characteristics make it the solvent of choice for critical cleaning applications such as oxygen components and service line cleaning, aircraft avionics and aerospace parts and servicing, precision optics, medical and high vacuum components and electronics.

ProSolv 5408e can be used in most solvent cleaning systems, one tank vapour degreasing or multi tank immersion / vapour tank systems using ultrasonics or flush cleaning for complex mechanical and electronic components with blind holes and channels and close mounted electronics or for removing grinding and buffing soils on surfaces.

ProSolv 5408e is soft on the environment and safer for users. High performance, improved cleaning, lower costs. Sustainable and secure for future use as your forever solvent.

ProSolv 5408e is a sustainable zero OPD and zero GWP solvent blend for high performance critical cleaning.  This new solvent ticks all the boxes with the perfect profile for a vapour degreasing solvent.

ProSolv 5408e lower boiling point, economical with energy and low solvent losses, faster production, reduced costs, easy handling. Exceptionally low surface tension to penetrate micron sized holes and close contact surfaces.

High KB value for removal of organic residues, compatible with organic and synthetic oils and most plastics and metals, non-flammable, with zero ozone depletion (ODP) and global warming potential (GWP).

ProSolv 5408e is the perfect replacement for trichloroethylene, nPB (n-propyl bromide), perchloroethylene or flammable solvents used in general engineering cleaning processes.


Where the manufacturing quantity does not justify the cost of specialised equipment this method already employed by machine shops manufacturing breathable oxygen valves etc for commercial, medical, and aerospace has been employed.

In a well-ventilated area with operators equipped with suitable PPE, masks, gloves and aprons.

Using Two or three containers or tanks with lids, suitably sized to fully immerse parts or basket of parts without the solvent overflowing. Fill tanks with ProSolv 5408e.

Using the counter current cleaning technique

Tank 1 is used to clean off the gross soils – swarf, cutting fluid, machining debris and polishing pastes from the part with agitation. Tank 2 is used as an intermediate rinse to remove oils and dilute contaminants carried over from tank 1.  Tank 3 is the final rinse to ensure absolute surface cleanliness.

At the end of each cycle drain Tank 1, flush clean and replace Tank 3. Refill with new solvent to become final rinse.  The used ProSolv 5408e can be transferred to a storage drum or tank for recycling. Allow the parts to drain and blow the solvent out of small drillings, blind holes etc with either nitrogen or oil free air. The Solvent will evaporate quickly leaving the parts oil free and sterile.

Cleaned parts must only be touched with clean gloved hands. Store / ship in clean sterile plastic Ziplock bags. The solvent will evaporate readily so keep the tanks covered when not in use.
NOTE: site the tanks in a well-ventilated area with extraction if possible.


When on site flush cleaning of tubes and piping systems is required all valves on the system to be cleaned should be removed, disassembled, and cleaned separately, with blanks installed. 

Flush cleaning

Ensure the area is well-ventilated with fans and extraction equipment in confined areas and operators equipped with suitable PPE, masks, gloves, aprons. A drum pump electric or hand operated with a flexible tube connection for delivering the solvent to the open end of the pipe or tubing is used to flush the internal surfaces. The other end of the pipe or tube needs to drain into tank where samples can be taken to determine when no particles are being removed and the emerging solvent is water white, completely clean. Using a fresh drum of ProSolv 5408e connect drum pump and the delivery tube to the end of pipe/tube to be cleaned using a screwed or compression fitting.

The drainage end of the pipe or tube should be fitted with a flexible tube into a tank or drain sump allowing samples to be taken in a glass bottle or tube at regular intervals to be sure when no particles or soils are being expelled. The colour of the solvent will change as oil and soluble contaminants are removed and flushing must continue until the flow is totally clear and water white.

At the end of the cleaning process use a dry nitrogen to purge any ProSolv-5408e that may be entrapped in
a blind hole, dead space, or any other places in the system. Use photo ionization detector (PID) testing, or other methods to determine when all the ProSolv 5408e used for cleaning is removed in the system that was cleaned at the discharge end of the system. Purging is complete and the system is clean when the ProSolv 5408e cannot be detected in the dry nitrogen purge gas exiting from the system.

After the system purge is complete and the system is clean remove the blanks and replace cleaned dry valves using new gaskets.

A wipe of the pipe/tubing surface at the inlet and outlet using solvent saturated lint free cloth completes the cleaning. If not connected immediately to other parts of the system enclose both ends of cleaned item to prevent recontamination.

Used ProSolv 5408e should not be reused for flushing but can be used as top up for vapour degreasing tanks or recovered for reuse by a simple distillation process. Removal from site should use licensed disposal companies.

Refer to the MSDS for storage, use, and health and safety Personal protection equipment (PPE).

Please visit our website for information about other uses and applications for ProSolv 5408e.

Visit for information about uses and applications for all EnviroTech Europe products.

For more advice, please telephone us on +44 (0) 20 8281 6370 or use our website contact form.

All products are supplied and supported by EnviroTech Europe Ltd. Manufactured in the United Kingdom and available on short delivery times through our dedicated team of distributors worldwide.

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