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R911370699 | PS6000/PRC7000 with water cooling
5.1.2
Circulation cooling with open cooling circuit
In open recirculation cooling systems, the dissolved and undissolved substances
in the water are thickened as a result of evaporation of the circuit water.
Thickening is understood as the increase in concentration of the ingredients in the
cooling medium. In addition, gases and solid particles are washed out of the
cooling air and introduced to the circuit water. Under these conditions - and
reinforced by the heat uptake in the heat exchangers - the precipitation of
suspended and dissolved solid substances, microbiological growth and corrosion
are especially encouraged.
The cooling circuit has to be topped up by supplemental water. The supplemental
water needs to be treated appropriately to restore the chemical and biological
balance.
The materials used comply with the minimum requirements stated in Section
7 Materials.
An open cooling circuit must be avoided for PSG xxxx welding transformers and
PS6000 or PRC7000 weld timers.
The closed cooling circuit is recommended as standard solution.
5.1.3
Flow cooling
The coolant media to be used for flow cooling include drinking water and natural
cooling waters. Monitoring of the water quality is recommended. Natural cooling
waters contain different percentages of salt and suspended matter. As a rule, this
involves the necessity of appropriate filtering measures.
If the water quality meets the requirements as per Table 4, Coolant definition, no
additional conditioning is necessary.
5.2
Pressure
The maximum cooling system pressure must not exceed 10 bar. The pressure
should be chosen as low as possible to allow the use of pumps with a flat
characteristic.
The maximum permitted pressure difference for a heat sink is 200 kPa (2 bar).
The arrangement has to be chosen so that the total length of inflow and outflow
line is the same for each PS6000 / PRC7000 device (refer to Fig. 1).
A water technical series connection of devices is not permitted because the
higher volume flow, which would be necessary for a sufficient cooling, increases
the risk of cavitation and abrasion.
The pressure drop per PS6000 / PRC7000 device is provided in the technical
data in Table 1: Necessary and supplementary documentation Rexroth PSI6xxx
Weld timer with Medium-Frequency Inverter / PRC7000 Process Resistance
Welding Control Instructions.
Bosch Rexroth AG
27/35
Cooling circuit
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