The Finn-Aqua service manual for our sterilizer states that Skyl-Tech, Inc. is the manufacturer of their drainline thermocouple feedthroughs. Is this correct and can we purchase replacement sealants from you?
Yes, this is correct. We have made the feedthroughs and sealants for Finn-Aqua since the early 1990’s. The sealant in question has a light green color and is approximately 0.4” diameter by 0.5” long with a 0.25” hole. They are directly available from us here in the USA. They can also be purchased from Finn-Aqua in Finland and Insteco in Ireland.
August 11, 2009 at 4:01 pm | Uncategorized | No comment
We need calibrated and certified thermocouples. Can you supply them?
We could, but we do not. The value of a calibrated or certified thermocouple is questionable because it must be calibrated while attached to your measuring system where it will be used. The system calibration encompasses and includes the data logger, the sensors (thermocouples), the calibration SOP, calibration baths/dry blocks, NIST traceable standards, technician training records, and a documentation trail for all of these items. Because we can only control these items at our site and can not control how you handle or use them at your site, we decline to offer calibrations. We do not offer certification because we can not control how you handle the sensors and for how long you use the sensors (at what temperatures, and in what conditions (high humidity)). This is why you must perform a calibration before and after each use to certify suitability. The procedures and regulations of your countries regulatory agency must be consulted and followed. We can guarantee that at the time we shipped the thermocouples, they met our accuracy specifications, they were of the specified type, and that the insulation was either FEP or PFA.
August 10, 2009 at 11:05 am | Uncategorized | No comment
How many thermocouples do I need for a validation study?
We often get asked for advice as to the number of thermocouples required by regulatory agencies for performance and operational validation studies. There are no required minimum numbers in any regulations. You justify the number in your validation protocols by analyzing the size of your vessel, the size of the components of your load, the number of components in your load and doing performance runs while moving the thermocouples to prove your assumptions on the location of the cold spots. The cold spots are the only locations you have to demonstrate the attainment of a minimum F0. In all of the other spots you are only showing stability and repeatability of the F0 above this minimum.
We had one customer who wanted us to supply 90 thermocouples in feedthroughs for a validation study in a lyophilizer. We declined and convinced the customer to do smaller studies to determine cold spots after reviewing the lyophilizer supplier’s design and performance data. All of the shelves were of identical design and the cold spots were in essentially the same locations.
August 7, 2009 at 11:41 am | Uncategorized | No comment
Why should I use stranded thermocouple wire instead of solid wire?
Thermocouples are not perfect and can produce many kinds of errors. One of the most significant errors is caused by non-uniformity of the wires. This non-uniformity exhibits itself in two forms: non-uniformity of the alloy in the wires along the length of the wire and non-uniformity in the crystal structure of the wire due to incomplete annealing or handling and bending of the wire.
Stranded wire addresses the second type of non-uniformity. Solid conductor thermocouple wire is stiff and difficult to handle. Getting it to conform to the desired paths inside a sterilizer requires that the wires be bent and sometimes severely kinked over a small radius to get the sensor tip into the desired position. After the run, the wires are straightened out which requires further bending. This bending and unbending causes the metal of the wire to work harden and crystallize. These crystals are of different sizes depending upon the amount of bending they experience. If the wire is an alloy such as Constantan, the crystals can actually cause the alloy to separate into different alloys and possibly crystals of the individual metals in the alloy. This results in non-uniformity of the wire, which causes errors. Stranded wire is limp and easily drapes and conforms around the load inside the sterilizer. It can be bent over a 0.5 inch radius and straightened without work hardening. As a result, it is less prone to non-uniformity errors due to handling and will have a much longer useful life.
July 28, 2009 at 9:47 am | Uncategorized | No comment