The regular examination of samples taken from the heat transfer medium circuit is an important precondition for the safe operation of a heat transfer system and BetrSichV (Annex 2) (German industrial safety regulation) requires an analysis at least once a year.
However, reliable statements can be made only then when the samples have been taken properly, representatively, and exactly. This requires the compliance with DIN 4754-1.
For the analysis it is very important to receive a representative and exact sample from the main flow.
The sample from the main flow is often taken during the normal operation of the system. Therefore, the oil is very hot. . From a hot sample however, the low-boiling components escape provided the sample contacts the atmosphere. The sample will then include less low-boiling components and in a following examination the heat transfer oil will appear better than it really is.
Therefore, the sample must be taken in a way that it contacts the ambient air until it has cooled down enough.
For this purpose, the sample must be taken from the hot, flowing medium in a characteristic point.
A sample cooler – like the one made by NESS – is a heat exchanger in which the medium flows through a stainless-steel spiral tube which is in a jacket filled with cooling water. This ensures that the sample is not taken under open or hot conditions.
Among others, the thermal oil sample is then examined by us for the three most important factors that are decisive for a good oil quality. These include flashpoint, acid figure, and Conradson value.
The indicators from analyses and a corresponding recommendation for acting – if advisable – will finally be communicated to you. On demand, our experts will contact you in person to work out an individual concept for further proceeding with the objective to increase safety, availability, long lifetime, and efficiency of your thermal oil system.
If you need any help with taking samples and analysing of your thermal oil, certainly we will be at your disposal as usual.
Using the NESS Sample Cooler, the oil sample can be taken under closed and cooled condition. It functions as a heat exchanger in which the medium flows through stainless-steel spiral tubes installed in a cooling water jacket.
No problem at all! Like all NESSessities, also the NESS Sample Coolers are designed as individual modules. Existing processes are not influenced. This concept allows an easy retrofitting also for already existing systems.
For instance, it is installed by means of one of our installation kits on the manometer valve on the outlet side using a T-connecting piece with U-tube for the connection of the manometer. A manometer valve is inserted instead of the Ermeto-valve. Preferably, the assembly takes place after heater pump.
With this, pay special attention to the following interface parameters:
| Sampling connection | 8mm Ermeto tube |
| Inlet temperature | max. 400°C |
| Pressure | max. 40 bar (g) |
| Cooling water connection (inlet/outlet) | Rp 1/2″ |
| Inlet temperature | max. 20°C |
| Pressure | max. 6 bar (g) |
Cooling water is needed for cooling of the thermal oil. The connection of the cooling water inlet and outlet can be established by hose connections. The cooling water outlet must be connected to a freely flowing out hose connection to avoid overpressure.
Furthermore, a sample vessel and a disposal vessel (temperature-resistant up to 100 °C) must be available.
At first, open the ball valve for the cooling water inlet and check if cooling water is flowing.
Carefully open the sampling valve and discharge only so much thermal oil in the disposal vessel until it is ensured that the thermal oil comes from the main flow and therefore it will be representative.
Only then fill the heat transfer medium in the sample vessel. After the extraction of the sample, the sampling valve must be closed tightly again. Now, also the cooling water inlet can be reclosed.
The sample cooler is maintenance-free. Occasionally, the cooler should be flushed with a suitable cleaning agent to prevent clogging.
Yes, the outdoor installation is generally possible, but it is not recommended. For instance, if there is the risk of frost, the sample cooler should be emptied completely. For this purpose, the water inlet must be dismounted and the cooling water which may be left in the cooler, must be discharged completely.
