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Laboratory gas piping system installation

A centralised gas system is an integral part of laborataries planning. Central gas distribution systems safeguard the gas distribution at the workplace.


The central gas system has many advantages that includes :

1) A constant gas supply - gases are readily available without the need to always wait for gas cylinder replacement. 

2) Gas hazard safety - monitoring of gas cylinders theft & leakage is easier. Gas storage can be locked to prevent theft a
nd unauthorised access. Gas detection system can be installed to monitor gas leakage.

3) Easier gas assets management - centralised storage & distribution
 system eliminates gas cylinders being scattered in various unsecured locations.


  An important part of managing the gas distribution to your labs includes gas piping consultation, design and installation for laboratories. Gas piping designs can range from simple & economical to sophisticated according to different needs and budgets.

Central gas supply systems designs for laboratories depends on accurate pressure control, flow requirement and contamination free gas piping components like high pressure gas regulatorpoint of use regulator, for gas distribution within the laboratory. The introduction of impurities like moisture, dust into gas piping system is detrimental to the analytical result accuracy for  instruments such as Gas Chromatograph GC, GC-MS, ICP-MS and Atomic Adsorption Spectroscopy. 


Gas piping and distributing system can consist of autochange manifold to ensure continuous gas supply and alarm system to warn facility manager or user of gas cylinders becoming empty. This feature is particularly useful for applications such as incubators, ICP-MS, GC-MC where interruption of gas supply will affect cell culture and analysis sequence. High purity pressure regulators are used to maintain the purity of the gas piping system. Stainless steel (SS316) tubing is used for high purity  laboratory gas piping system.


Consultancy services will be provided with the right design and specification for gas piping installation for various laboratories' needs to construct a safe and contamination free gas piping system at competitive costs. 


With a central gas storage and gas distribution in place, a safety system consisting of gas detectors and alarm system will make monitoring easier. Emergency shut-off valve with actuator or solenoid valve can be designed into the gas piping system to eliminate gas leak events.


Gas piping guide : Design of Inert Gas Systems


Introduction

Inert gases, such as nitrogen are used on process plants for a number of purposes - such as purging equipment and inerting equipment.  The most common inert gas used in industry is nitrogen, but carbon dioxide and argon are also encountered.  Although usually non-toxic, inert gases can displace oxygen creating an asphyxiating atmosphere.  As the common inert gases are colourless, odourless and tasteless, they can build up in the atmosphere without the victim being aware.  This makes them very dangerous.  This article provides some guidance on safe inert gas system design.

It should be noted that this is only an introduction to the subject.  The reader is advised to seek professional support when designing an inert gas system.

Why Inert Gases are Used

Inert gases are used to create a non-reactive atmosphere, it must be non-flammable and should prevent any adverse chemical reaction.  For example, providing an inert environment to prevent the decay of food.  Several industrial gases are used for inerting.  The most common is nitrogen, as it is cheap however argon and carbon dioxide are also used.  Other inert gases include the other ‘noble gases’ (i.e. helium, krypton, neon and xenon) – although these are only used in specialized applications.

The main use of nitrogen in the process industries is to purge air or hydrocarbons from equipment before start-up, during normal operations and during shutdown.  It also has a range of other specialist applications, such as in the manufacture of semiconductors, applications in the pharmaceutics and to regenerate catalysts.

Argon is much less frequently used than nitrogen because it is more expensive.  However in some applications, nitrogen is insufficiently inert (e.g. nitrogen can cause nitriding of metals), in which case argon can be applied.  Its main use is as a shield gas for welding.  For some applications, such as in the food industry, carbon dioxide is used for inerting.  However, its use is limited as it is mildly corrosive when wet.

Dangers of Inert Gases (Asphyxiation)

Inert gases are dangerous.  Whilst these gases are generally non-toxic, they do displace air, making them asphyxiants.  Accidents caused by oxygen depleted atmosphere can be very serious, and sometimes prove fatal.  Normal oxygen content of air is 21% (volume basis).  Breathing air at levels only a few percent below normal will result in impaired judgement.  At oxygen concentrations below 10%, there is a risk of asphyxiation leading to death in a matter of minutes. 

To make matters worse, there is generally little warning.  As nitrogen and argon are both colourless, odourless and tasteless, the gas can build-up without the victim being aware.  In addition, the absence of carbon dioxide suppresses the breathing reflex.  Thus the victim can suffer asphyxiation suddenly without even realising it. 

In addition to asphyxiation, some inert gases present other hazards.  Liquid nitrogen can cause ‘cold burns’, whilst carbon dioxide is toxic.  Further discussion of these subjects is outside the scope of this article.

Inert Gas System Design

Introduction

The designer must aim to reduce the dangers of asphyxiation as far as possible.  The most effective approach is to eliminate the hazard completely – can the use of an asphyxiant gas be avoided? If the inert gas has to be used, can the hazard be reduced? 

The designer should then consider how to isolate the gas from the working environment, as well as the use of engineering controls, such as gas detectors linked to system shutdown.  Finally, if these options are not sufficient, the plant needs to develop safe operating procedures.  This can be achieved by protecting workers using Personal Protective Equipment (PPE), supported by safe systems of work.  The following should be considered during the design of the inert gas system.

Mechanical Integrity

Equipment and pipework containing the inert gas should be robust and should meet best engineering practice.  Flanges should be avoided as they can leak.  Pipelines should be welded as far as possible.  Equipment and pipework should be pressure tested before use, as well as after maintenance.  Any unused pipelines should be physically disconnected from the live system. 

The operating pressure of the inert gas system should be kept as low as possible.  In the event of a leak, this lowers the rate of gas release.

Location

The designer should consider where inert gases are likely to accumulate.  Gases that are heavier than air (such as argon) will settle at floor level and at low points.  The release of gases with similar densities to air (such as nitrogen) will tend to result in localised regions of depleted oxygen.  Particular locations to consider are the following:

1.  Gas storage areas

Inert gases are often stored in liquefied form.  Spillages of liquefied gas will rapidly vaporise, releasing large quantities of gas.  Ideally, storage areas should be well ventilated and away from working areas.  Access to the gas storage area should be restricted.  The area should be equipped with gas monitoring and display warning signs.

2.  Relief and ventilation system outlets

Relief and vent lines should be clearly identified and should be piped to a safe open air location, away from working areas. 

3.  Rooms where inert gases are used 

Use of inert gases in enclosed areas should be avoided if at all possible.  They should be well ventilated and equipped with oxygen monitoring equipment.  Access should be restricted to trained operators, preferably not working alone.

4.  General access areas

General access areas (e.g. corridors) present a particular hazard as there is no means of restricting who enters.  General access areas and inert gases not mix. 

Ventilation 

The designer needs to consider the likelihood of an escape of inert gas and whether it will be adequately dispersed.  Inert gas systems which are outdoors rely on natural ventilation to dilute and disperse the gas.  For indoor areas, dispersion has to be done using reliable forced ventilation.  Ventilation rates to disperse the gas may need to be above that required for human comfort.  The design of the ventilation system is not straightforward and the designer is advised to seek professional advice.

Operation and Maintenance

Whilst the hazards from the use of inert gases can be reduced during the design, often they cannot be eliminated.  The remaining hazards must be managed by operating procedures. 

Confined Space Working 

Confined spaces are areas which are not usually occupied and where asphyxiant gas could build-up.  A common example is a vessel which is normally inerted and needs worker access for maintenance.  The best approach is to avoid entry in the first place – for example, it may be possible to clean vessel or take samples remotely.  Unfortunately, this is not always possible. 

Confined space working is a potentially dangerous activity and needs to be planned carefully.  It is outside the scope of this note.  Before planning confined entry, the reader should seek professional advice.


Contact us to install an easy to use and safe gas piping system.