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What is Monitoring of a BS9251 Fire Sprinkler System?

ire Sprinkler Systems sit dormant until they are required as a fire has started. However, there are critical elements of the sprinkler system that could affect how the sprinklers operate which without monitoring you wouldn't know have been compromised.

For Example, Isolation Valves. Under the Current BS9251:2014 isolation valves should be lockable and left locked in the open position. However, once the system has been commissioned / serviced there is no way of knowing if that lock has been removed or the isolation valve closed. In these circumstances, someone may have isolated the sprinklers for maintenance, while refurbishment works are being undertaken, an issue on the water supply etc. If the isolation valve is not returned to the locked open position it is possible that the water supply to the sprinklers had been isolated, meaning when the sprinklers are required they would not operate.

Monitoring of isolation valves on a domestic water system is not required because if an isolation valve was isolated the occupant would realise there was an issue as when they opened the tap water would not come out. However as sprinklers sit dormant, if the sprinklers had been isolated, the occupant or building owner would be none the wiser until the sprinklers were required. At this point in time, its too late. Having the Sprinkler system isolated could lead to serious consequences hence why it is so important to ensure isolation valves are in the open position, there is sufficient stored water available and the booster set is online and does not have a known fault.

The revised BS9251:2020 due out in October this year requires all Isolation Valves to be electronically monitored to ensure valves are in the open position. However, why should we wait until a British Standard tells us to do this when it is common sense it should be done straight away and possibly save more lives.

How do we Monitor Sprinkler Systems in accordance with BS9251?

Sprinkler monitoring is the continuous supervision of critical elements of the system. These elements are as follows:

  1. Isolation Valves - to ensure the valve is in the fully open position

  2. Tank Level Switches - to raise an alarm in the event that the required stored capacity falls below 90%

  3. Booster sets - to raise an alarm in the event of a Fault or Loss of Power.

FloWatch manufacture a dedicated Sprinkler monitoring system which will monitor all of these points and raise alarms in the event that the system has been isolated, there is insufficient stored water or a fault or loss of power on the booster set. However in this article we look at the other components required to successfully monitor the sprinkler system.

We will look at each element separately:

Isolation Valves

There are two main types of Isolation valves on Domestic and Residential Sprinkler Systems in accordance with BS9251. On each zone, most commonly 1 per floor, is a residential riser valve set consisting of Pressure gauge, Isolation Valve, Flow Switch and Test Point. The second type of isolation valve is a standard lever valve used to isolate supply, most commonly used in BS9251 Sprinkler System to isolate an individual apartment.

To enable the Isolation valve to be monitored, a switch is fitted to the isolation valve to ensure the isolation valve is in the fully open position. When the isolation valves begins to shut, the Switch sends a signal to the monitoring device to warn that the isolation valve is not in the fully open position.

Figure 1. Monitored Residential Riser Valve

Rapidrop Global and IPS Flow Systems both sell monitored Residential Riser Valve Sets and stand alone monitored isolation valves. These would replace the standard valve sets and enable them to be connected to a monitoring system.

Tank Level Switches

A level switch in a tank traditionally has two main functions, high or low level. High Level Tank Switches raise a warning if the ball valve has failed and too much water is in the tank causing it to overflow.

Low Level Tank Switches are installed near to the point where the tank runs out of water and prevents the booster pump from running without a supply of water. This in turn prevents the pump from damage.

In the context of Sprinkler Monitoring, its too late to notify that the tank is empty. We want to know when the tank falls below 90% of the capacity required. This will allow preventative action to be taken before we get to the point where the tank is empty and could possibly be too late!

Therefore the tank level switch would be installed at a height equivalent to 90% of the required capacity for the Sprinkler System. In this instance when using the FloWatch Monitoring system a standard Low Level Tank switch with a normally open contact can be used that are widely available.

Booster Sets

When a towns main provides insufficient water pressure and flow, a booster pump is used to provide sufficient supply. This can be either directly off the main or with a stored water supply. The pump will be fitted with an automatic test facility, such as the Martech Watchdog, which will have a fault output. This output can be connected to the FloWatch monitoring system which will raise an alarm in the event of a pump failure. An alarm will also be raised in the event of a loss of power to the pump.

Want to know if the Sprinklers have activated?

The Flow Switches that are required on the Sprinkler system normally serve the purpose of initiating the emergency procedures, i.e raising an alarm on the fire alarm panel. However, this is all dependent on the fire strategy and connection of flow switch to an appropriate fire alarm should always be done in accordance with the fire strategy for the building.

However, the FloWatch Monitoring system can also be used to monitor flow switches so that the system is aware when the sprinklers are active. This can be extremely useful to building owners in certain circumstances.

For example, If the building had vulnerable people, maybe assisted living accommodation, where the occupants may be hard of hearing / sight, but the configuration of the sprinkler system meant that the Flow Switch was linked to the apartments fire alarm and not a communal system due to the strategy being stay put, it would be beneficial for the building manager to be made aware of a sprinkler activation to enable them to check with the occupant and if need be raise the emergency protocol. It could be that apartments are regularly empty or prone to damage then the FloWatch Sprinkler monitoring system has the facility to monitor a normally open flow switch giving the building manager / owner a total overview of the sprinkler system allowing them to take remedial action prior to an activation of the sprinklers and reactive measures in the event of a sprinkler activation.

Sound Confusing?

It's not confusing when you have FloWatch on your team. We will assist with the design of the monitoring system, selecting compatible products and providing full wiring details. If you provide a copy of the fire strategy report we can also advise on the correct configuration of the alarm strategy and integrate the monitoring.

Contact us today to discuss your project or 01737 481070.


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