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Safe And Effective Isolation: Is The Answer Double Isolation In Just One Unit?

DBB3 Double block and bleed Bellows Sealed Stop Valve 07

Unforeseen repairs of critical plant equipment in a hospital or healthcare facility brings with it the nightmare scenario that multiple essential processes are put out of action when they are needed most – risking patient safety. Angelo Giambrone, Business Development Manager at Spirax Sarco, highlights the importance of safe and effective plant isolation.

Hospitals and healthcare facilities depend on steam for a multitude of applications including sterilisation and hot water provisions to keep patients comfortable, surgical tools sterilised and wards clean. When it comes to isolation, whether for maintenance tasks or critical repair jobs, safety and effectiveness are key.

Carrying out safe and effective isolation whilst minimising disruption to the day-to-day working of the facility will always be at the forefront of any maintenance manager’s mind. Therefore, it is important they understand what options they have available to them.

The risks of staying single

In England, there are 152 acute healthcare trusts, each responsible for managing and overseeing numerous healthcare facilities. Some of the older hospitals under their care may still be making use of a single valve adjacent to the plant as a means of isolation.

There may indeed be a second isolation valve somewhere in the plantroom, but it might not be close to the plant in question, it may isolate other items of equipment and be accessible only through a myriad of pipework. Therefore, plant isolation can bring with it a number of challenges for maintenance managers.

Single valve isolation within plant rooms of hospitals or healthcare facilities is no longer adequate, as all the responsibility to provide a safe, leak-free environment in which to work, fall onto that one valve seat.

Even a minor leak could result in an unsafe working environment and an inability to fix the problem that required isolation in the first place – leaving sites without heating, hot water or other services critical to their operation.

The Health and Safety Executive (HSE) has issued guidance that states that single block and bleed (SBB) should only be used in conjunction with a complete detachment of the plant; in effect, spading off the steam supply to guarantee isolation. Alternatives should be seriously considered.

DBB3 Double block and bleed Bellows Sealed Stop Valve 02

DBB3 Double block and bleed Bellows Sealed Stop Valve 02

Doubling up

Double block and bleed isolation provides a leap forward towards safe and effective isolation. Traditionally this solution has involved the use of two main-line valves separated by a spool piece, into which a small bleed with a third valve is fitted.

With both main isolation valves closed and the bleed open, plant maintenance can be carried out by maintenance personnel, safe in the knowledge that there should be no pressure on the second valve. Any slight leak present from the first valve would be vented via the bleed.

Due to the extra valves, traditional double block and bleed installations require more space than a single isolation valve. When considering an upgrade to an existing single-valve installation, this can be a challenge if plant room space is already at a premium. Time and money would need to be invested in rearranging pipework to accommodate the extra valves, if indeed the space were available.

Even with brand new installations, the extra pipe lengths would need to be taken into account in the design, increasing the overall plantroom space required.

DBB3 Double block and bleed Bellows Sealed Stop Valve 08

DBB3 Double block and bleed Bellows Sealed Stop Valve 08


Two become one

The alternative for maintenance personnel requiring reassurances that they can progress with the task in hand safely and quickly, is to make use of an all-encompassing DBB isolation valve unit such as SafeBloc™.

SafeBloc™ is a safe, reliable and effective double isolation solution, helping sites operate to the best practice as set out by the Health and Safety Executive (HSE). Due to its compact design, it can usually be fitted into the space made available by the removal of a single isolation valve, without pipework modifications. This allows work to be carried out safely and quickly, resulting in a return to peak operation with minimal downtime.

The entire installation has fewer flanged connections when compared to using separate valves, thus minimising the potential number of flange leak paths. Additionally, an added benefit is the valve’s use of bellows sealed stems, resulting in zero stem emissions and eliminating the maintenance with conventional gland stem sealing.

The safe choice

When it comes to safe and effective isolation for maintenance and repair processes, without the concerns of extended shut-downs due to ineffective isolation, SafeBloc™ can bring you peace of mind.

To find out more about safe and effective isolation, please visit: sxscom.uk/SafeBloc

Spirax Sarco

Spirax Sarco is a leading provider of steam and thermal energy solutions headquartered in the UK

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