Why should I test my heat exchanger?
In order to comply with HACCP requirements, processors need to identify Critical Control Points and/or areas within their production facilities that may cause product contamination. Examination of internal surface areas in plate and tubular heat exchangers, coolers and pasteurisers has become common practice in the liquid food processing industry in order to comply with Due Diligence.
How often should I examine my heat exchanger?
Heat exchangers, most positioned within the production area, are regularly checked for cracks, normally six monthly, searching for pinholes, cracks and other defects inherent in this equipment. Defects may occur ay any time during production, or when the machine is opened for servicing; some defects can be detected even when the equipment is new, either from the manufacturing process when cracks emanate from the pressed areas, or from poor fitting.
These defects may cause product contamination in the form of bacteria or chemical leakage into the product via the adjacent service/regeneration side of the exchanger.
I have used traditional methods to test heat exchangers, what is the best methodology now?
As heat exchangers have inherent defects that can contaminate the product, there have been may test methods developed over the years to help prevent this. These include; pressure testing, gas testing (Helium), conductivity testing, and dye testing. Inconsistencies in some of these methods will be described shortly.
Easytesters have developed Hexteq to address these inconsistencies.
I would like to detect cracks before they leak, is it possible?
Traditional test methods can only Pass or Fail a heat exchanger; they cannot determine the size of the defect or the leakage rate.
The Hexteq test method is able to accurately measure the size of a defect. Easytesters have determined that with a defect size of less than 20 microns and under a defined pressure, there will be no leakage or cross-contamination of the product. With this information, the processor is able to predict when a heat exchanger may fail and prevents unnecessary shut-down of an exchanger.
Can you prove the accuracy of the test?
Traditional methods have been used for many years and not normally validated for accuracy under processing conditions,
Hexteq has proven University validation using laser drilled test holes in an industry standard heat exchanger, independently verified with a Scanning Electron Microscope.
How safe is the equipment that you will use for the tests?
Traditional methods use electrically operated equipment, either 110v, 240v or 415v; chemicals and gases are also used. Some of the common risks involved include, electric shock, chemical contamination, heavy lifting injuries.
Hexteq uses lightweight, battery operated electronic sensors and transmitters only.
How much downtime is needed for the test?
Traditional methods may take many hours for one heat exchanger test, given the amount of equipment needed and the methodology used.
Hexteq is able to examine a heat exchanger from both sides in approximately one hour.
Would the size of my heat exchanger affect test sensitivity?
All traditional methods are volume dependent and the larger the heat exchanger, the less sensitive the test will be.
With Hexteq, the size of the heat exchanger is not a factor for this methodology as the sensors are searching for defect size and leakage volume in micro-litres. This is a critical improvement from traditional test techniques.
I have been told that if the test is carried out from one side only, it is possible to miss major defects; is that correct?
It has been proven that some cracks or defects may ‘close’ when pressurised from one side, making them undetectable and then ‘open’ when pressurised from the other side. This is due to plates either pushing together at critical defect areas, or cracks open like a door from one side, then close from the other side.
Traditional methods cannot normally check from both sides as it is too time consuming to remove the donor gas or chemical from the recipient side.
Hexteq is able to do this by simply switching pressure from one side to the other.
Traceability is very important to me, how can this be done with a heat exchanger test?
Traditionally, a certificate will follow the test.
Hexteq introduces full traceability for the condition monitoring of heat exchangers. This includes GPS location of the test, date and time stamp, graph showing leakage rate and size of any holes inside the heat exchanger. For ISO approved production facilities this enables clear and concise auditing.