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A guide to liquid leak detection


All too often the liquid leak detection system takes second place to other alarm systems, resulting in systems being reduced from the original specification or cut altogether from the budget. This is primarily due to the systems not being fully understood and users not fully understanding the risks that they could suffer from a leak. If we were to be honest the same decisions wouldn’t be taken with the likes of say a fire alarm system. In fact if you tried it probably wouldn’t be allowed! The thinking here is water as opposed to fire, is, in most cases not life threatening, but boy can it disrupt your business!

The popular term “Water Detection” is actually inaccurate as systems can detect Water, Acids, Aqueous chemicals and Fuels, therefore “Liquid Leak Detection” would be a more fitting term.

Cable Detection

Just an egg cup full of water from a ceiling mounted air-conditioning cassette unit dripped straight into this banks PABX disrupting business for in excess of 5 hours.

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Here we try to point out some of the pitfalls with the design, specification and installation of a comprehensive and reliable System.

In many instances the person charged with the procurement of the liquid leak detection system has no experience whatsoever of leak detection and this is even true of many consulting engineers. So it would seem that the most simplest and reliable route is to approach a manufacturer, don’t! And I mean this; if you do you are limiting your choices to just one system and after more than 17 years in the industry we know that no one manufacturer has all the answers. You are best approaching an independent water detection company which has no ties with the manufacturers at all and who will propose the best system or systems to suit the applications, trust us it’s not unusual for our company Aquentis to install different manufacturers systems in different locations within the same building.

So what are you trying to protect?

OK silly question…… or is it? Why do you need, or think you need liquid leak detection? So “step 1” is to establish exactly what it is you are trying to protect, this is going to dictate the type and level of detection needed. A little time taken now to analyse and determine this will ensure that the system will perform the required function and will ultimately dictate the eventual method and cost of the protection you design into a system.

Is it specific Items such as computers, artwork, electrical equipment or archived documents that you want to cover or the infrastructure supporting them? Put simply if you have a small computer room do you want to protect the computer and install your chosen sensing medium around that piece of equipment or do you want to protect the room, the power and data systems which support the computer, in which case you would trace the pipe work, Air-conditioning units and any other probable source of leaks which influence the correct operation of the computer.

Protecting Items is relatively straightforward, but if it is the actual infrastructure you wish to protect, well that’s a different matter! You will need to consider any possible leak that could disrupt any element of the support infrastructure, this is called “Risk Assessment” A leak in areas other than those containing the items such as plant rooms, corridors, toilets, washrooms, lift shafts, can all interfere with the normal running of a business.

Risk Assessment, where do I begin?

Even the smallest leak in the wrong place can have disastrous consequences to the normal running of a business. Just a few drops in the wrong place and your phone system is out of service or your entire computer network down.

1. List and prioritise the Items requiring protection

2. Determine what amount of water would be needed before damage occurred.

3. Determine the possible sources of a leak in the immediate vicinity.

4. Try to determine the likelihood of a leak from the possible sources you have found.

5. Ascertain sources of a leak close by.

For instance an overflowing sink on the floor above or a cleaners closet next door could cause water to seep or flow into the critical area. Other potential sources are water tanks, perimeter heating systems, toilets, kitchens, air conditioning units, coffee machines, and fire hose reels.

6. Are important Items on a plinth, legs or raised from the floor.

7. Do any pipes run directly over or under the critical items, and are there any joints or valves which might fail.

8. For high level services, has a drip tray been installed and is it adequate and drained.

9. Consider what disruptive effect on business a leak would have from any of your identified sources of a leak.

10. Consider the possible and the most likely cause of a leak in your particular building.

Would it be from freezing, mechanical failure (washers, glands, valves etc.), breakage’s, seepage, or from accidents, miss-use or vandalism.

If once you have carried out the above you can honestly say that there is no risk from a leak or flooding, then you can sleep easily at night. But beware, your findings might just surprise you, particularly if you’re in a multi-tenanted building and you never knew that the tenant upstairs had a vending area right above your server room.

What level of protection do I need?

If a drip increases to a flow, then a flow could become a flood and…

The highest level of protection is in most cases detecting an initial leak at it’s source, by this I mean an individual valve, joint or pump etc, this is referred to as “Close Protection” however, unless there are such items adjacent to the Items you intend to protect, a more general approach may be needed.

Basement Flooding

Basement Flooding

It’s a sad fact that companies and organisation prefer to archive away valuable documents and contracts in the basement. Assuming that your quick enough and think on your feet you might just be able to get these documents to higher ground.

But if your not or the leak occurs at night or at the weekend you might just have some interesting days ahead!

Taking into account your Risk Assessment the potential sources of leak’s and their geographic relationship to the Items you wish to be protected should be known to you. Now try and establish the most likely path the water will take should a leak occur.

OK, having established the above, determine which, if any, each potential leak source poses:

1. A direct & immediate threat

2. An indirect, but likely threat

3. An indirect & unlikely threat

4. An unlikely but possible threat to the Items requiring protection

5. No threat at all

Obviously each of the above may vary dependent on the severity of the leak and this must be taken into account when determining each category.  Consideration should also be given to the possible disruptive effect any leak would have in its path to the Item. By this I mean the infrastructure. For instance let’s say you have ascertained that the main water tank for the building is in a roof plant room and your computer room is several floors below, you may surmise that a leak would pose an unlikely but possible threat as in 4 above. But have you considered the Electrical Riser which runs the full height of the building. If water was to reach this even at plant room level and enter Distribution panels or Busbars the electrical supply to your computer room could be affected.

So having determined the above, you should now have a list of:

1. Items to be protected

2. Potential sources of a leak

3. Amount of water or level needed before damage occurs

4. Likely path water leak/s would take

5. Proximity or path of leak in relation to Items to be protected.

6. Severity of the disruption to operations each leak would cause

By taking into account the importance of each Item together with its vulnerability to the leak threat, you should now be able to determine:

  • The amount of protection needed, i.e. from complete protection (no water contact) to a ‘level’ (small depth – say 1 to 10 mm) of water.
  • The amount of time required from the alarm being raised to establishing and stopping the leak’s source.
  • The type of detection medium and the leak location capabilities (often referred to as resolution).

The type of water detection medium (device) will vary dependent on the leak’s source, the area’s covered and the resolution required along with the level of water to be detected.

What type of water detection equipment should I use?

Water Detection devices can be divided into 3 main categories:

Point Detection

This consists of a detection device containing water sensitive probes or an Infra-Red Photocell.

They are normally positioned or fixed to the wall/floor adjacent to or beneath the potential leak source or item to be protected.

They can be mounted either horizontally or vertically so as to be as close as possible to the optimum position to detect any water. Water contact with the unit is required before the detection circuit is activated.

Areas where normally used
  • Tanked/sealed floors, where a build up of water can occur.
  • Adjacent to a potential leak’s source.
  • Drip Trays etc.
  • At lowest point in sealed area’s such as dry sumps.
  • Lift pits.
  • In locations which are exposed such as plant room floors which haven’t been afforded a raised false floor and are too dirty for sensing cables.

Pad Detection

This consists of a flexible PVC sheet containing water detection circuitry and covered in a highly absorbent material envelope to aid water absorption. They can be used with or without the material envelope dependant on the sensitivity required, they can sometimes be supplied as single or double sided dependent on the application. This Detection device can be used in areas to detect the smallest ‘Drip’ should this be required. It should be noted that not all manufacturers offer this item as it is probably the least used detection medium, however a good independent water detection company should be able to adapt one from one manufacturer for use on another’s system.

Areas where normally used
  • In suspended ceilings, beneath pipe joints/valves ect.
  • In suspended ceilings, resting on ceiling tiles above the Items to be protected.
  • Actually on top of ‘Items’ to be protected such as equipment racks.
  • Wrapped around pipe joints etc.
  • In false floors, beneath potential leak source’s.
  • In plant rooms below valves or pumps

Cable Detection

This consists of a specially constructed cable, capable of detecting water anywhere along its length. Different manufacturers use different construction methods and materials and frankly these range from simple cables which you could make in your home workshop to sophisticated extruded polymers. All have one thing in common; water has to contact them to cause an alarm. Sensing cables need to be chosen for the environment in which they are being installed and this is a major pitfall when selecting a cable based system from just one manufacturer, this is mainly because he is unlikely to tell you that his cable is not ideal for part or all of your application.

Areas where normally used
  • Beneath raised false floors
  • Used as a barrier fixed in the path of any water. e.g. across the base of a step in a stairwell. (Note: protection from foot traffic will almost certainly required).
  • Suspended or laid beneath runs of pipe work.
  • Actually attached to pipe work. (This practice is known as tracing).
  • Clipped around the periphery of the base of any ‘Item’ to be protected.
  • Installed within Electrical control panels & Busbar enclosures.
  • Fitted within drip trays, particularly those without drains.

In order that you understand just what the differences are you will need to understand the construction of the different cables and the problems they encounter, in almost all circumstances is better to contact an independent adviser who can talk you through these differences and advise you as to which is more suitable for your application.

What Liquid Leak Detection Control Panel?

OK now we have a whole new set of considerations. Just what do we expect our system to do? Ok! We expect it to make a noise, an occasional light on the front to tell us it’s doing something would be nice, and, oh yes a means of signalling that there’s an alarm.

All manufacturers will describe their panels as state of the art and try and convince you with specification points and features. As ultimately you pay for these features it is worth nothing unless it’s what you want, a typical example of this is the 4-20mA transmitter offered by several manufacturers, why pay for this if your not going to use it. If you need this functionality fine buy it. But if all your going to do is connect to a set of clean relays, what’s the point?

Functionality obviously plays a major part in the final decision as what panel to buy but as a rule of thumb never over specify unless there is a real chance that the advanced features will be needed within 2 years of the installation date. The number of zones is also a stumbling block, obviously if you have decided a Longline system is what is required then this is not a concern, however if you require zones then you will need to work out how many zones you require to provide adequate coverage and then how many you need to provide for future use, 20% spare capacity is a respectable figure to achieve.

Cable Detection

Water detection modules such as the Aquentis Leak detection module LDM-230 and the Leak detection module LDM-24 offer a simple way to provide water detection for a low cost. These liquid leak detection Modules are often found within OEM equipment such as Air-conditioning units and BMS outstations.

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Most manufacturers supply a range of one, four, eight and sixteen zone control panels to which any combination of detection devices can be connected.  Most are microprocessor controlled and monitor each zone and it’s detection devices for water contact or circuit/cable break.

Almost all control panels include audible and visual warnings, and incorporate leak and fault relays for remote alarms or BMS connection. However individual zone leak relays are nearly always an optional extra. Circuitry to differentiate between an alarm or fault condition is available in most but not all panels as is battery back-up. It is well worth considering panels which have a battery stand-by feature built in as some items of equipment are more prone to leaking when they are de-energised. Any number or combination of detection devices can be connected to most panels, but be aware that some manufacturers products are not interchangeable, so if you require a certain type of detector this will influence your choice of control panel.

Larger capacity control panels up to 128 zones are available but require professional installation as the wiring can become complicated. It is also worth remembering that adequate zone information in the form or a chart or drawing must be provided and kept by the panel on the larger systems as valuable time will be lost looking for the detected leak if it’s location cannot be found quickly.

Longline panels which give a distance reading allowing a leak to be located quickly over large distances are also available. These are normally installed in sensitive area’s which are mission critical to the business or to cover important items or assets. Because of their cost these systems are better suited to the larger installation or where cost is of little consequence. The accuracy of these systems mean that a leak can be located over several kilometres to within ± 1 metre. The latest breed of these panels use digital technology to communicate with a small integrated circuit within the sensing cable so that more than one leak can be located, a problem with the older systems!

Liquid leak detection panels

Liquid leak detection panels

Liquid leak detection panels such as the Aquentis ALD126 offer sophisticated features that allow comprehensive liquid leak detection on a zonal basis which can be tailored both in sensor type deployed and sensitivity.

Universal point detectors, more a device than a panel but some are capable of monitoring one or more slave sensors. They are useful in situations where only a few areas require monitoring and/or there is a ‘System’ (BMS, security, fire) present with spare capacity, a ‘stand-alone’ point detector (Universal point detector) can be used.  This unit requires only a 12 Volt DC supply to operate and they include a clean contact relay output for connection to the existing system. These detectors are almost identical in size to a normal point or probe detector and can be used in most areas

Leak detection modules are small units which have been designed primarily to go inside other manufacturer’s equipment; these are often used within Air-conditioning units and electrical process control panels. These unit’s often have no controls or sounder on them as it is assumed the host equipment will handle the alarm annunciation. A good example of these is the Aquentis LDM-230 water leak detection module.

What’s important to me?

Only one person can answer that… Me!

Anything which will interrupt the normal operation of your business, cause stress, anxiety or destroy a valuable asset is important to you.


The above illustration gives you an idea of area’s commonly covered within what we would call a normal working environment. Increasingly though businesses are requiring more custom and unique facilities in which to carry out their operations. If for one minute you have doubts about what is required, call in an independent Leak Detection company such as ourselves, over 17 years experience in the industry will ensure that the system will be adequate for your specific need’s.

Examples of some ‘Typical’ areas to be monitored

Plant/Tank Rooms

As above, most of these areas have sealed and tanked floors and the method of detecting a leak is the same. However, because the floor area may well be much larger, it may be possible and advantageous to detect any leak nearer its source. Point or pad detectors can therefore be placed at strategic positions, beneath tanks, adjacent to pumps or valves etc. Very few plant rooms are maintained at a level of cleanliness which is suitable for sensing cables although some do exist, due consideration must also be given to mechanical damage either by foot traffic or maintenance activities. Don’t consider sensing cables if the floor is clean because it is mopped regularly, this will cause an alarm which will soon discredit the system for those who rely on it.

False and Raised Access floors

Most computer suites and a growing number of modern offices have raised access floors to allow airflow from the air handling units and easy cable routes for telecommunications and power systems. In these case’s it is vital that any leak is detected quickly, if not, a significant build up of water can occur out of sight, if allowed to continue without being checked it may cause serious damage to electrical and data connections, which in turn may impact on the companies ability to continue operations. Detection devices should be positioned beneath or adjacent to all potential source’s of a leak. It is also worth considering what path the water will take and whether it can seep through the floor structure to below and what is sited below!

Toilet/Wash Room

Here there are many areas of a potential leak, but in most cases the floor is tiled and tanked. Therefore if a leak occurred, water would initially collect and build up on the floor before exiting the area. The most likely exit route for this water, if the floor is sealed, will be beneath the bottom of the entry/exit doors or through mechanical pipe risers or ducts behind toilets, sinks or urinals, a water detector or detectors strategically positioned alongside or adjacent to the inside of the door frame, or sensors within the ducts or risers would therefore be the most effective location to detect any significant leak.

Suspended Ceilings

Hidden pipe work may occupy areas within the voids created by suspended ceilings. Most pipe work, if not exposed to freezing conditions, poses little threat of a leak unless influenced by outside factors such as installation of cabling or further pipe work. In the unlikely event that a leak occurs, it will probably come from a joint or valve along the pipe run and not from the pipe itself. Again, look at what you wish to protect. If for example, vital equipment, goods etc. are present in the room and directly below a pipe joint or valve, then placing a Detection device such as a pad sensor below this joint/valve within the suspended ceiling will pick up any such leak.

Heating Systems

Most heating systems, radiators and pipe work run around the perimeter of rooms. Unless the floor is of the raised access variety, water detection devices can be located adjacent to each valve. However, each radiator or valve should be assessed individually, in that should a leak occur at that particular point, would it directly affect any of the ‘Items’ requiring protection? It may well be that only a few individual points may require detection located near them.

These are just a few area’s which I have chosen to give as an indication of the considerations which should be made, obviously every application must be considered based upon it’s own particular requirements. Water detection is a specialised field and you aren’t expected to know all of it’s intricacies, just where to go to find out!