When carrying out the process of sterilising liquid products in containers, it’s important and necessary to be able to monitor the product temperature during the sterilisation cycle. Whether you are using thermocouples or PT100 resistance thermometer probes, the optimum point of measurement is considered to be the central point within the product. This is irrespective of the shape and size of the container. For accurate product temperature therefore it is essential that the temperature probe is located in this position.

However, problems can arise without a firm, reliable method that enables you to ‘fix’ the temperature sensor in the right location. If the sensor is not fixed in place then there’s a chance that it will shift position by the end of the cycle, making temperature readings potentially inaccurate. This is usually caused by the movement of the product cart whilst being loaded into the chamber. it can also be caused by the temperature affecting the expansion/contraction of the product as well as the temperature sensor.

Thermal Detection, a company in the North East manufacturing industry, developed the GL45-BC in order to overcome these issues. It utilises a standard Duran GL45 bottle, cap fitted with a captive integral probe connection which can’t be removed. The connector itself is made from Grade 316L stainless steel. When used with stainless steel sheathed thermocouples and PT100 resistance thermometers, a Teflon® sealant that is housed within the connector is used to retain the position of the temperature probe and prevent it from shifting about during sterilisation. All you have to do is insert the temperature probe into the desired position and slightly tighten the cap nut by hand in order to secure the probe in place.

As an added bonus, removing the temperature probe once the sterilisation cycle has been completed is both fast and simple. It’s just a reversal of the insertion method, enabling you to secure and loosen the probe with ease.

Probe Mounting Bottle Caps


 Where a simple thermocouple wire is to be used instead of a stainless steel sheathed thermocouple assembly, the GL45-1 from Thermal Detection offers a solution.

Thermal Detection offers the Duran bottle cap, which uses the same captive Grade 316L stainless steel connector as the GL45-BC. This time, however, a silicone rubber sealant is used to seal against the smaller size thermocouple wire, outer jacket. A cannular in the form of a Teflon® tube with a 6.0mm outer diameter and a bore of 3.8mm is permanently fixed to the underside of the GL45 bottle cap.

The Teflon® cannular can be supplied to the customer at a specified length, but if preferred it can also be supplied at a length of up to 300mm long, allowing the customer to cut to their desired length instead. The Teflon® cannular also ensures that the hot junction of the thermocouple wire is retained in the desired location throughout the sterilisation cycle ensuring accurate temperature readings. In instances where more than one location point of measurement is required, the cannular can be supplied with up to two holes cut in the side for the fitting of additional bare wire thermocouple temperature sensors. However, customers should bear in mind that it is recommended that no more than three thermocouples be used with GL45-1.

Both the GL45-BC and the GL45-1 probe mounting bottle caps are suitable for use with round glass Duran® bottles of 100ml, 250ml, 500ml and 1000ml sizes and square Duran® bottles of 250ml, 500ml and 1000ml. Similar caps are also available for use with the Corning® range of square polycarbonate bottles of 150ml, 250ml, 500ml and 1000ml sizes.

If you’d like to know more or consider making a purchase, check out Thermal Detection’s site for more product information and technical documents.