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The hazards of using Leak Detection Fluids (LDFs) - and why you should use Bicknell bubbler

The hazards of using Leak Detection Fluids (LDFs) - and why you should use Bicknell bubbler.

There are a number of potential hazards involved in the use of LDFs. These include:

  • LDFs damaging both the cylinder or valve materials, immediately or over time potentially causing unexpected and sudden catastrophic fail.
  • LDFs posing potential flammability risks, especially with oxygen.
  • LDFs components/contaminants leaving residue upon drying (for example, in the valve outlet) posing potential risks with container contents to the user in the case of medical and food gases.

Detection fluids materials compatibility

Depending on the chemical constituents of any LDF, the overall question of materials compatibility needs to be considered. One of the possible constituents of LDFs is the ammonium radical, that in association with oxygen and water is frequently responsible for Stress Corrosion Cracking (SCC) of copper-based alloys such as brass and aluminium silicon bronze. These copper-based alloys are often used for manufacturing cylinder valves. Ammonia can be introduced into LDFs by third parties who repackage LDF into aerosol cans. The original manufacturer of the LDF could be unaware of this contamination.

The corrosive effects from certain LDFs coupled with the stresses to which a cylinder valve is subjected due to mechanically applied forces, residual stresses, and gas pressure can be sufficient to result in SCC.

It is difficult to specify exactly and with a high level of confidence the minimum amount of ammonia needed to trigger SCC. However, it is known that moisture films on brass surfaces are capable of dissolving residual ammonia from atmospheric contamination, resulting in SCC.

Of further consideration is the possible presence of halide ions (usually chloride) in LDFs. Though not necessarily harmful to steel or brass surfaces, they do cause significant damage to aluminium alloy cylinders in the form of pitting. Excessive exposure to chloride ions in the form of sea water of certain aluminium alloys (for example, diving cylinders made of AA2001) has been disastrous if the alloy has not been heat treated correctly. Even cylinders made from the much more corrosion resistant alloys of the AA6000 series experience pitting on the top surface of the cylinder’s neck after successive applications of certain LDFs.

Leak detection fluids oxidizer/flammability risks

LDFs are used to check external and internal leaks of cylinder valves. When LDFs are used to check for internal leaks, the repeated action of application and subsequent drying of an LDF in the valve outlet is one of the causes of an ignition in oxidizer service. This is due to the progressive accumulation of residues, especially in the valve outlet where the LDF is introduced to check for seal integrity. Subsequent use of the valve exposes this residue to a high-pressure gas stream. This is especially true if the LDF is made from a household soap-based solution that can contain mineral oil, vegetable oil, or fatty acids.

The results for many commercially marketed LDFs sold as “safe for oxygen”, “oxygen safe”, etc., have shown that in every case their dried residues were easy to ignite in high pressure gaseous oxygen or liquid oxygen.

Medical and food gases

The LDF shall be evaluated for potential for build-up of those contaminants in the gas stream and subsequent inhalation by end-users of medical and food gases. Any LDF used to check for leaks that could encounter medical and food gas should be manufactured with materials that do not present a health or inhalation hazard to end users.

NOTE — LDFs manufactured with ethylene glycol are typically not acceptable for medical use

Reference EIGA Doc. 78/20 - Leak Detection Fluids with Gas Cylinder Packages

The Bicknell leak detecting bubbler totally removes all these hazards described above all that is needed is 1” of tap water and it’s 100% safe to use to detect leaks on any Valve, having been tried and tested by one of the leading Gas Company in the world ‘employed as best practice’ by BOC/LINDE for 16yrs of design and prototyping, continuous improvements to enhance the bubbler to find the smallest of Leaks quickly increasing productivity, recognized by industry as best practice

The water is kept separatee from the Valve with absolutely no Fluid on the Valve, so no possible flammable Residue left behind.

We can custom design a Leak Detector for any commercially available cylinder Valve if not already in our extensive inventory, we can deliver worldwide, no matter what corner of the world you are in we can supply,

No order too small or too large.

If you were a big concern with multiple filling plants across the globe then you could potentially order one big batch to your main depot, then distribute to the relevant filling plant, potentially saving thousands on delivery cost and customs as they could be sent with other parts going to the same depot.

We have the infrastructure and the ability to fill any size order, and everything is made in house, so consistency is always there.

The bicknell bubbler – Unique to the Industry – only available from Bicknell Engineering!

Visual – Gas Bottle – Leak detection

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