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measurement. The pressure/ temperature relationships of steam mean that temperature measurements can be extremely helpful in establishing existing steam system pressures, while thermal tests include infrared thermography, contact thermal recorders (thermocouples), and infrared point radiometers (pyrometer). Each has pros and cons. For example,


while thermal testing devices will detect the temperature of the steam line ahead of the trap and at the discharge, they can only estimate existing steam pressure. Similarly, during infrared testing, the


effect of the piping composition and/ or insulation material on emissivity must be considered. So while measuring equipment is a vital weapon and must be an integral part of a steam system testing programme, it cannot provide a definitive answer. It demands analysis and a true appreciation of the capabilities and limitations of the equipment. The third and final approach


comprises acoustic or ultrasonic inspection. Providing a versatile and accurate steam system diagnostic tool,


An incorrectly installed steam trap will be prone to steam leakage.


ultrasonic testing allows the operator to hear sounds inaudible to the human ear. This type of equipment receives a high frequency signal (typically between 20-100kHz) that is converted to an audible sound with the aid of headphones. Ultrasound devices that detect


T


he range of traps available, coupled with the sheer size of many steam operations and the complexities of detection, mean that it is not uncommon for leaks to be missed or misdiagnosed.


high-frequency sounds are a simple method of testing steam trap stations and are extremely accurate in detecting the distinctive high frequency noises made during the proper operation of a steam trap. The sensitivity of most high frequency monitoring equipment allows the testing person to hear not only completely failed steam traps (blowing steam), but even leaking steam from a trap in operation. Clearly then, while there are


numerous diagnostic tools available, most rely on interpretation and specialist knowledge. Knowing what to look for – and listen to – and what subtle variations mean will significantly reduce the chances of misdiagnosis, and so the experience of the technician is therefore of paramount importance in the process.


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