Frequently Asked Questions


Why should I test my Residence times?

In order to comply with HACCP requirements, processors need to identify CCPs (Critical Control Points), and/or areas within their production plant that may cause product contamination/failure. Examination of pasteurisation holding time by validating regularly has become common practice in the liquid food processing business in order to comply with Due Diligence.

How often should I validate my Holding Time?

Pasteuriser holding tube times are normally checked every 6 months, as any slight variation due to product fouling, pump reliability, valve performance etc. may affect the holding time, if the said time is reduced high bacteria counts may be evident, if the time is increased there may be product quality issues (taste for example). These problems may not be detected by simply checking phosphatase, as with skimmed milk for example most of the enzyme clings to cream.

I have used traditional methods for testing my Holding times, what is the best methodology now?

Many years ago, a system was developed in USA to carry out holding time tests, this involved stopping production, removing the holding tube, fitting conductivity sensors, then filling the system with water and injecting salts for time checks from beginning to end. EIT International has launched Pasflo WSN to address the inconsistencies. Pasflo has been introduced to test the holding time of product during production. It involves placing 4 sensors outside of the holding tube (none intrusive), then slightly raising product temp by a couple of degrees for a few seconds, then using a clever superimposing technique, calculating the time in minutes.

If the Pasflo test simply measures a temperature variation against time, why can’t I do this myself?

EIT International has researched this in detail, and when taking into account laminar and turbulent flows and relevant flow laws, it is important to superimpose images at both ends of the conduit to conclude a correct residence time. Hardware modules and software calculations are necessary to make the test accurate. Technical detail is therefore prohibited.

What are the environmental issues with testing?

Traditional methods have many environmental issues as the chemicals need to be manufactured for the test, then disposed of after test. EIT International’s systems are all electronic sensors that can be used for many years without any consumables, so the most environmentally friendly.

I would like to also calibrate or validate my flow meter, is it possible?

Using traditional methods this would not be possible as the test will show a time from beginning of tube to end of tube only. The Pasflo WSN method is able to accurately measure the Pasteurisation holding time of the tube and also during production, measure the flow rates at varying velocities. A big advantage over all other systems.

Can you prove accuracy of the test?

Traditional methods have been used for many years and not normally validated for accuracy under processing conditions. Pasflo has a proven validation using known holding tubes and an industry standard heat exchanger, independently verified with an industry standard and independently calibrated flow meter.

How safe is the equipment that you will use for the tests?

Traditional methods use electrically operated equipment, either 110v, 240v, or 415v, and also chemicals. Some of the many risks include electric shock, chemical contamination, heavy lifting injuries. Pasflo uses lightweight battery operated electronic sensors and transmitters only, therefore no risk.

How much downtime is needed for the test?

Traditional methods may take many hours to test 1 holding tube due to inconsistent results, this is all down time for production. The test should take an average from 3 checks within 0.5 seconds of each other, this is very difficult to do with inconsistent readings. Pasflo WSN can be done during production and has proven accuracy, requiring minutes to carry out successfully, and no loss of production.

Will your Inspector be trained and qualified?

In accordance with our Quality manual, all Inspectors shall be trained in the use of the relevant Test equipment and methodology, by way of annual training and Qualification certification. Ask to see the Inspector’s Qualification Certificate at any time.

Is your equipment calibrated and serviced regularly?

In accordance with EIT International’s ISO 9001 Accreditation, all test equipment has unique numbering and is returned to base annually for upgrading when necessary, servicing and calibration. When calibrated, the said equipment will expire and stop working after 12 months, this assures annual calibration.

Traceability is very important to me, how can this be done with a holding time test?

Traditionally, a Report will follow the test, that is it! Pasflo has introduced full traceability for the condition monitoring of Holding times, this includes GPS location, date and time stamp, graph showing test details, and for ISO approved organisations this is imperative.