Once upon a time an engineer had a requirement to measure the flow of liquid through ...
Taking the Heat out of Fire Pump Testing
Category: Fire Pump Testing | 13/07/2006 - 14:26:34
Most modern commercial buildings incorporate a number of essential safety features. Two such areas of importance are automated fire detection and extinguisher systems. These play a vital role in ensuring that all individuals are protected in the unlikely event of a fire and that the potential for damage to property and equipment is kept to a minimum.
The problem faced by engineers is how to ensure that the system is correctly maintained and most difficult of all, how to prove this to the regulatory bodies. One of the principle areas of concern is that in the event of the alarm being activated, sufficient water should be pumped through the sprinkler heads to ensure correct operation of the system. To this end one of the key annual maintenance requirements for the fire system is to service the fire pumps. This is done to ensure that they are in full working order and capable of delivering the specified amount of water over the designated time span. Having conducted the servicing the question still remains as to how engineers can verify the true installed capacity of the pumps and prove this for insurance purposes?
The Loss Prevention and Certification Board (LPCB), is an organisation that provides guidance to both industry and insurance companies on the operation and maintenance of fire pumps and sprinkler systems. The LPCB has produced a series of requirement documents for all areas of fire protection including guidance on fire pump testing, automatic sprinkler system testing, and verification of flowmeters on fire pump systems including the testing of the sprinklers themselves.
The LPCB maintains a list of approved sprinkler contractors who are able to verify and certify systems based on their guidelines and then issue certificates of conformity to the end customer. These certificates are then used as proof to Fire Brigades, Local Authorities and Insurance Companies that the system meets the appropriate standards and has been installed correctly.
According to LPCB guidelines the output of fire pumps should be "verified at the rated speed over a range of flow rates"i. The document provides specified tolerances for measuring and verifying the Maximum Pump Head, the Head Flow Curve and the Net Positive Suction Head Curve (NPSH). However, the document does not specify how the all important flow data should be gathered, indicating only that "The bypass flow rate and pump temperature shall be recorded".
It is at this point that Katronic Technologies are able to provide a solution for verifying these all important pumped flow rates. Katronic is a company specialising in non-invasive ultrasonic flowmeters. The Katronic clamp-on instruments are traditionally used for industrial applications such as power generation projects, however more and more frequently the technology is being employed for building services applications such as energy metering, air conditioning evaluation and CHP system measurement. The latest area of development in the technology is to provide a solution for fire pump testing.
The Katronic system involves the use of the KATflow 220 portable ultrasonic flowmeter as a temporary method of evaluating the flow output from fire pumps. The KF220 pump testing kit incorporates two analogue 4-20 mA active inputs. These are used to connect to and provide loop-power to external pressure transmitters in order to have a full diagnostic check on the pump characteristics.
Furthermore the integral wall thickness probe means that it is possible to determine the precise pipe installation conditions prior to conducting a survey. As well as the portable device Katronic are able to offer the KATflow 110, which is a flowmeter for permanent installation on systems where regular flow tests are carried out. One of the key benefits of these meters is that they can be commissioned without any requirement for pipe modification and can be fitted on any pipe work from 10 mm upwards.
It is sometimes the case that a flowmeter may have been installed at the same time as the commissioning of the sprinkler system. However, it is possible for these devices to drift out of calibration with time and changing system conditions. Rectification of this problem would involve substantial cost and effort in order to calibrate the meters correctly. Furthermore, the removal of the existing instrument would necessitate compromising the pipe work, which would leave the fire system offline or at reduced capacity, which is undesirable and potentially dangerous. In contrast to this the KATflow range of flowmeters can be installed without taking the system offline.
According to the LPCB guidelines all installed flowmeters on fire pumps systems should be proved to be measuring within certain tolerances, for example on a flow of 800 dm³/min the flowmeter should be able to measure to within ±40 dm³/min, which is equivalent to 5% of measured valueii. In fact the whole test program is based on a tolerance of 5%, which given that the uncertainty of the KF220 portable flowmeter is +/- 3% of measured flow rate proves what a useful tool it would be for identifying potential problems.iii
For applications where the requirement to measure the pump output is only temporary the KF220 portable flowmeter provides a truly flexible solution. One of the key advantages is that the meter will display and log, flow rates; total flow and flow velocity information, all of which is essential for properly evaluating pump performance. The large datalogging capacity of the Katronic pump testing system means that the flowmeter can simultaneously log flow and pressure information without the requirement of a costly external datalogger. All the measured information can then be neatly presented to the user through the Katronic KATdata dedicated software, or by using a standard Windows-based spreadsheet.
The information provided by the flowmeter is not only of use from a pump output point of view. By testing system pressure and flow rates simultaneously it is possible to investigate pump efficiency, not only on fire systems but also in a huge variety of other applications.
With escalating energy costs and recently introduced environmental legislation, huge cost savings can be made by ensuring that all pumping systens are running as efficiently as possible and that any problems are rectified through preventative maintenance before they become a serious issue.
As well as being used on fire pump evaluation applications the pump testing kit could be used by pump supply companies for commissioning purposes, by service companies for pump evaluation and by any company who is looking to monitor pump efficiency or power consumption. As well as the analogue inputs, the flowmeter can also be equipped with PT100 temperature sensors in order to evaluate air conditioning and heating system performance in facilities of all sizes, from large industrial units through to hospitals, schools and district heating systems.