Safety Cooler

Safety Cooler Bloksma PDT-type

Charge Air Cooler and Lube Oil Cooler


In case prevention of intermixing of fluids becomes an important issue it is strongly recommended to use the Bloksma Double Tube (DT) safety cooler. The Bloksma DT safety cooler excludes the risk of intermixing of fluids caused by leakage of the tubes. In case a leakage occurs, a detection system is activated which enables the user to take adequate measures to avoid intermixing of fluids or leakage into the environment.

  • Bloksma Safety Cooler PDT-type
    Bloksma Safety Cooler PDT-type

The principle of the Double Tube cooler is fairly simple. The single wall between the 2 fluids is replaced by 2 walls with an intermediate circuit. Any damage in one of the tube walls will result in a filling of the intermediate circuit. This filling is detected and results in an alarm signal.

As alternative for the double tube cooler the use of a secondary circuit could be considered. This alternative however needs a second heat exchanger. This secondary circuit needs conditioned cooling water, extra pumps, piping valves etc. The required heat exchangers are larger due to an adverse LMTD (Logarithmic Mean Temperature Difference) and, as a consequence, more expensive as well as in investment as operation.

All design options used for single tube heat exchangers are also possible with the double tube construction, so different material combinations and cooler constructions are possible, depending on the fluids used.

To realize this principle of 2 walls with an intermediate circuit, an inner and an outer tube are assembled into one physical tube. The outer tube is on the inside provided with longitudinal leak detection grooves. The inner tubes are mechanical bonded over the full length against the outer tube to ensure a perfect metallic contact. Also 2 tube sheets on each side are used instead of one.

The grooves are in open connection with the space between the two tube sheets.

In case of oil as primary fluid, an increased efficiency is obtained by using externally finned outer tubes, resulting in a compact design.

The materials of the tubes can be different. The outer tube is preferably made of copper. In case contact between copper and cooling medium is not allowed it will be possible to provide the tubes with a tin (Sn) layer. It is obvious that the thermal calculation is also based on the material-choice of the tubes.

The construction of the Double Tube cooler does not require specific measures for the cooling system, such as a minimum operating pressure.

To detect any fluid in the intermediate space, leak detection equipment is required. A special connection between the 2 tube plates is provided for mounting the leakage detector. The principle of the leakage detector is based on a change in capacity between 2 conductors. A switch, which is connected to the alarm system, is activated. This leakage detector is normally included in the supply.

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