Pressurised water temperature control units up to 160°C

All elements required for control and automatic monitoring such as push buttons, contactors, thermal relays for the pump motor, circuit breakers as well as the temperature controller are housed in the unit’s switch box. Temperature control uses a PID controller with heat-neutral-cool settings. The electronics are so designed that heating and cooling signals cannot be activated at the same time. This makes the controller extremely energy efficient.

When using semi-conductor contactors, the automatic safety devices and/or fuses cut the power supply in the event of an overload or short circuit within the protected component (e.g. heater).

Thanks to its high thermal capacity and environmentally-friendly nature (uncomplicated disposal), water is popular for use as a heat transport medium. The thermal capacity of water is around 4.2 kJ/kg, double that of heat transport oils. This means that significantly more energy can be transported and a more stable mould temperature achieved at a lower flow rate. Water also has a much lower viscosity compared to oil at around 1 mm²/s below 250 °C. This allows for more turbulent flows to be achieved at lower flow speeds. Turbulent flow is needed to ensure a faster exchange of heat between the heat transport medium and the relevant surfaces (heating elements, coolers, mould channels, inside surfaces of rollers, reactor walls, etc.)

As one of just a few heat transport mediums, water also has the advantage that its heat transfer properties are almost entirely independent of the temperature. This allows water to be used with a large range of temperatures. Water quality plays an especially important role in pressurised water units. Dissolved salts, chlorine content that is too high, a pH value that is too low, or the use of copper pipes and cavities can lead to corrosion, limescale or material fatigue. Chemically treated water is often essential when using it in industrial processes. In using this, it is critical that the additives used are suitable for high temperatures and that they do not decompose or split into acids at temperatures above 100 °C and do not form explosive vapours.

Tool-Temp places great value on ensuring robust construction. Pressurised water systems exclusively make use of permanent pipe joints. These are made using highly automated bending machines at the plant in Sulgen. The housing is fully enclosed so that zero contamination can take place. Heaters are placed under minimal load and the ratio of load on the heating surface to flow rate is optimised. Critical components such as coolers and flow rate sensors are produced in our own facilities. Starting with the design phase, special attention is given to the materials used. Without exception, stainless steel is used at every single point that will come into contact with water.

The following safety elements are integrated into all pressurised water units from Tool-Temp:

• The check valve prevents water from flowing backwards if the pressure in the circuit is higher than the mains supply pressure.
• Two safety valves monitor the rising pressure. The first valve switches off the heating, the second opens the circuit when the pressure is too high to force a drop in pressure.
• The manometers show both the system and pump pressures.
• The flow rate sensor monitors circulation of the circulation medium to the consumer.
• The pressure release ensures that the temperature control circuit is depressurised before the unit is decoupled from the consumer. When the unit is unpressurised (solenoid valve open) and the temperature is below 80 °C, the consumer can be emptied using suction.

Alongside the maximum temperature, the pressurised water series from Tool-Temp can also be divided into two groups in relation to cooling. All units feature indirect cooling as standard. There is an additional group of units which also feature direct cooling alongside the indirect cooling. Below 80 °C, the models with two cooling systems can be switched over from indirect cooling using a pipe bundle heat exchanger to direct cooling. A solenoid valve opens, allowing cooling water to flow directly into the water tank. This form of cooling mixes the cooling water with the process water. Excess water leaves the unit via the cooling water outlet. These pressurised water units can be used in a variety of applications due to their excellent cooling power across their entire operational range.

The primary advantage of pressurised water units lies in the high heat carrying capacity and excellent heat transfer properties of water. Compared to oil heat transfer mediums, water can transport much more energy. The wide range of operating temperatures achieved by Tool-Temp pressurised water units, as well as the direct cooling function, makes these units suitable for a wide range of applications. They are used for heating tool moulds in the plastic industry, controlling the temperature of rollers in the printing industry, and temperature control for extruders in the chemical, pharmaceutical and food processing industries.