Know Your Numbers: Mathematics of Gaseous Extinguishing Systems

Subscribe for the latest industry news, technologies and resources.

We care about your data in our privacy policy.

By starting with the numbers and mathematics of gaseous extinguishing systems, Coltraco are leading the way in the fire industry.

31˚C – CO2’s critical point: the temperature at which CO2 turns totally from liquid to gas.

CO2 is permanently under 720 psi or 49 bar of pressure ie nearly 50 times atmospheric pressure (by comparison a cup of water at sea level exists at 1 bar or 14.5 psi). Its state changes under increased temperatures to one that is neither a liquid nor a gas.

50-55˚C   –  critical points of FM-200® and Novec™1230 (turning from liquid to gas).

Gases under pressure are often effectively considered by the industry as single and passive cylinder columns of solid material from the perspective of their monitoring following installation. Whereas being under pressure and constantly changing under temperature they should be considered as active and dynamic systems requiring constant monitoring. These are not passive systems therefore; they are dynamic ones, and all dynamic systems under pressure need constant monitoring.

14520 – the ISO standard regarding fire systems from installation with regard to room integrity through to maintenance and inspection of contents

ISO 14520-1:2015(E) specifically states in Contents Indication that – Means shall be provided to indicate that each container is correctly charged and in At least annually, or more frequently as required by the authority, all systems shall be thoroughly inspected and tested for proper operation by competent personnel. Under ISO 14520 where gaseous extinguishing systems have to be designed in relation to the discharging agent hold-time (if the room cannot hold the agent because of leaks the agent will disperse and not extinguish the fire) and discharging agent peak pressure (if the pressure is too high for partition walls or suspended ceilings they will be blown apart or damaged and possibly destroying the room integrity). At the design stage of a fire extinguishing system rooms are tested for room integrity by positively pressurising a room and detecting escaping pressure to verify that the room itself into which the gaseous extinguishant discharges on actuation can both hold the agent after its discharge and hold its pressure on actuation. The fire system is then installed and commissioned. However, over the next 10 years no further tests are made on ultrasonic room integrity testing and the cylinders merely hydrostatically tested to ensure they can cope with their design pressure limits. How can one be sure therefore that on actuation the room will hold the discharged agent to extinguish the fire and its partitions and ceilings are capable of withstanding the pressure of the agent on discharge?

5% – loss of agent above which it is deemed unacceptable in liquefied gaseous extinguishing system and thus requires refilling. 10% – loss of pressure above which it is deemed unacceptable in liquefied gaseous extinguishing systems and thus requires refilling

The risks of accidental discharge or leakage is recognised within the regulations.  BS EN ISO 14520 -1:2015(E) reasonably assumes that the execution of its provisions is entrusted to people qualified and experienced in the specification, design, installation, commissioning, testing, approval, inspection, operation and maintenance of systems and equipment, and who can be expected to exercise a duty of care to avoid unnecessary release of extinguishant. The assumptions in the installation, commissioning and maintenance of gaseous extinguishing systems is that they are highly pressurised but risk leaking and discharging. The regulations that sensibly underpin this assumption aim to identify their leak identification at an interval of every 6 months. Cylinders accidentally discharge. CO2 can cause fatalities if it does. 1% of pressure gauges fail and 25% of valves too. Essentially, it is known in regulations that the gaseous systems leak and need to be maintained. Given that the gaseous systems are designed specifically to the individual need of that room, building e.t.c, then a 5% loss of agent may mean that they would not fully extinguish the fire. What if there are also leak sites in the room? The likelihood of the gaseous system effectively extinguishing the fire gets lower and lower. – The paragraph points from Chapter 5 in the IMO SOLAS FSS Code which details how vessels’ fire extinguishing systems should be checked for leaks

A ships Officers & Crew are not qualified to undertake CO2 servicing as it requires the dis-mantling, weighing and re-installation of the complete system which must be done by a licensed organisation when the ship is alongside. The code states that; “means shall be provided for the crew to safely check the quantity of the fire extinguishing medium in the containers.” To implement the IMO SOLAS FSS code, portable liquid level indicators such as Portalevel™ units are used on-board, allowing the crew to meet the code between servicing

1.5mm – the accuracy which Portalevel® and constant monitoring Permalevel® Multiplex can find the liquid level of agent in cylinders to.

26 seconds – The average test time to identify the liquid level in any liquid gaseous cylinder using the Portalevel® Max.
The UL approved Portalevel Max is designed to inspect the content of Fire Suppression System Cylinders of CO2, FM-200™, Novec 1230, FE-13, FE-25, NAF S III, CEA410, Halons and a range of other extinguishing agents. The device is a quick, accurate and efficient method of inspecting cylinder content. Portalevel® MAX builds on Coltraco Limited’s 30 years’ experience in designing, manufacturing and supporting Ultrasonic Liquid Level Equipment.  The unrivalled quality of the Portalevel, have resulted with units operating throughout the world.

0.06mm  –  the size of leak site able to be detected by Portascanner® 520 in Room Integrity.

Assuming 2 metres of water above the leak of this size, the water flowing through the hole will sufficiently fill 4.64 cans of soft drinks per day.

Using ultrasonic technology this the Portascaner® is able not only to pinpoint precise leak locations, but to determine their leak apertures as small as 0.06mm with a tolerance of +/-0.02mm, making it by far the most accurate device for this function. The Portascanner® also provides an interpretation of the seal for desired locations, labelling them either watertight, weather tight or full leakage site as appropriate. The advantages of being able to accurately detect the exact leak locations and size are self-evident when considered alongside the importance of reaching Peak Pressure for clean agent fire suppression to be effective.  The immediate use of the Portascanner® lies in its improvement of the final stage of room integrity testing – the search for leak sites in the case of a leakage excess – for which it can vastly improve accuracy and operational efficiency.

RS232/RS485 – communications capabilities Permalevel® Multiplex offers including dry contacts, 4-20mA relay for constant monitoring of liquid level.

24/7, 365 – continuous monitoring of gaseous systems and the room integrity

Permalevel™ Multiplex, is designed as a fixed 24/7 system to monitor anything from 5 to 700 cylinder level points. It is a modular system and each module will cater for up to 16 level points. The Permalevel™ Multiplex is the first system worldwide that is capable of monitoring the liquid level of critical fire suppression cylinder systems on a constant basis. The unit can be easily installed on new systems or retrofitted to existing systems, and can monitor up to 16 level points simultaneously. The system has a remote display showing the status of each cylinder, as well as the ability to link to remote local alarm or indication method. It can also remote link the status back to any Central Monitoring Station. The Permalevel Multiplex is designed to ensure that fire suppression systems are always fully operational and that no accidental discharge has occurred, which could affect the effectiveness of the overall fire protection system in the event that it is required for use. This allows a facility to have complete confidence that they are fully protected.

0.1mm± – The accuracy tolerance of both the Portagauge® 3 and Portagauge® 4 ultrasonic thickness gauges

Metals corrode and pressure gauges stick. Annex F of ISO 14520 specifically guides our industry as to these risks stating every 6 months the following checks and inspections must be performed: 1) externally examine pipework to determine its condition; replace or pressure test and repair as necessary pipework showing corrosion or mechanical damage; 2) check all control valves for correct manual function and automatic valves additionally for correct automatic function; 3) externally examine containers for signs of damage or unauthorized modification, and for damage to system hoses. The quick, simple and hardy Portagauge ™ 3 allows accuracy of ±0.1mm even on corroded, challenging and some plastic surfaces. It utilizes single echo technology which allows the unit to maintain accuracy even on corroded or challenging surfaces. It is ideal for corrosion, rust or condition inspections and is a highly dependable unit. The Portagauge™ 4 is able to ignore surface coatings such as paint. With easy calibration and no zero-ing required, the Portagauge 4 is ideal for effective and efficient thickness gauging applications

5% – Accuracy tolerance of the Portasonic® handheld ultrasonic clamp-on non-invasive flow meter at flow rates over 0.5m/s

There are a number of issues to be considered in regard to maintenance such as corrosion, flow rate and obstructions that may adversely affect the effectiveness of a fire sprinkler system . Portasonic® is easy to use and is proven to reduce maintenance time and costs. It can also be used for testing fire hydrants. The flow is calculated so that there is always enough to control a fire taking into account the size and construction of the building and the goods stored in it or its use. Accurate flow data provides the chance to make energy saving measures by fine tuning the systems. The Portasonic can measure this through self-adapting proprietary signal quality tracking, allowing the system to automatically optimally adapt to the pipe material and flow profile in both directions. The ability to conduct spot checks on the sprinkler system at mandated intervals ensures the full integrity of a sprinkler system.

1% – the accuracy of the agent weight calculated by the Portasteele® through liquid level identified using Portalevel® compared to weights determined by manual weighing methods

The Portasteele® Calculator is an advanced calculator application, that converts the liquid level height of C02, NOVEC™ 1230 and FM-200® liquefied gaseous extinguishant agent readings taken on an ultrasonic non-destructive liquid level indicator device into the agent weight/mass.  Furthermore, the Portasteele® can convert an expected agent weight back to the required liquid level allowing users to anticipate where the level should be.

109  – the number of countries Coltraco has supplied equipment

Integrity is our defining value. Performance is its consequence. Coltraco is experienced and globally renowned.

Get in touch

You can reach us anytime via phone or email, we aim to respond to all enquiries within 24 hours (excluding weekends and bank holidays)


Come say hello at our Technical Laboratory.

Coltraco Ultrasonics
NETPark Research Institute
Joseph Swan Road
TS21 3FB

United Kingdom


Monday - Friday (excluding bank holidays) from 8:30am to 6:00pm, UK.

Tel (Sales & HQ): +44 20 7629 8475
Tel (Technical): +44 1740 618 240