Case Study: Ammonia Gas Detection in Refrigeration Plant

April 8, 2016 One of IGD’s clients from the industrial refrigeration sector approached the company to see if we could help with a particular monitoring problem. Whilst this client purchased addressable Ammonia gas detectors for plant room monitoring they were also looking for a solution to cold store monitoring. Typically the Ammonia evaporators located in the cold stores could be down at -30 Degrees Centigrade and conventional point leak detectors would have issues. The company had used sampling systems from some of IGD’s competitors in the past. These systems sequentially sample and with their associated pumps, filters, solenoid valves etc were complex and costly to maintain with potential service issues. They also suffered from freezing sample lines and were not continuously monitoring as they sample sequentially. The systems our client had used had infra Red Ammonia detectors but these had range ability and accuracy issues at low ppm levels with slow response. Having built many speciality sampling systems IGD were acutely aware of the problems. Sampling systems can be complex with many moving parts all of which work to reduce reliability. Infra Red gas analysis, whilst a proven technique is not always the best solution depending on the target gas and how strong an infra red absorber its is coupled with the available path length. Solution: IGD’s solution was to use their addressable technology to design small multipoint sampling modules which could be mixed with conventional addressable point detectors. These modules use the latest piezo pump technology to minimise moving parts. Each sample line has its own pump which is monitored for flow. Pumps are turned on sequentially to sample each gas line to a common detector. A module consists of four gas lines, this being seen as the best compromise to be as close to continuos monitoring as possible. Electrochemical Ammonia measurement cells have both good range ability and reliability but can suffer from drift at higher ranges. IGD’s solution was to have a fifth piezo pump on each module which draws sample gas through a clean air scrubber. This allows the detectors zero to be checked and corrected on each cycle. The result is a small format addressable four port sampler with excellent zero stability, fast response and good range ability. Up to 32 sample modules could be fitted onto a single addressable cable run allowing distributed sampling around a site. Thus was born IGD’s TOCSIN 150 series addressable sampler modules. Our client was impressed with the result and these units have been in reliable service for a number of years. Use of the TOCSIN 150 series samplers has spread to many other applications. Clean rooms benefit from the samplers minimum intrusion into the room. The same is true for background Anaesthesia monitoring applications, glove boxes, high bay monitoring and many more. Tocsin 150 series monitors can be fitted with Infra red or Electrochemical sensors from IGD’s extensive range. Many more applications now benefit from the development of the TOCSIN 150 sample module.