Water cooling system for induction equipment: a closed loop of clean water that carries heat to plant water through an exchanger

01

Water temperature, pressure and quality limits set by the induction equipment

Ajax Tocco states that its induction equipment needs cooling water between 75 °F and 105 °F, because water that is too cold causes condensation that can short-circuit electrical components and water that is too warm lets equipment overheat, and that pressure should stay constant between 30 and 70 psig, since brief pressure drops de-energise the equipment. It reports that hardness above 100 ppm CaCO₃ and suspended particles above 10 ppm impede flow and cooling through mineral build-up, that pH should be held between 7.0 and 7.5, and that dissolved oxygen drives corrosion and biological growth. [1]

The two makers differ on fill water. Ajax Tocco fills its closed loops with deionised or distilled water for low conductivity, which it calls essential for cooling solid-state power supplies; UltraFlex recommends clean distilled water but says never to use deionised water, which it states damages aluminium, copper and bronze fittings, and treats conductivity that is too low as unsuitable. [1] [3]

UltraFlex states that up to 80% of problems with induction heating equipment trace to water, recommends isolated loops with plant water kept out of its equipment, allows a 30% non-conductive ethylene glycol mix and phosphate-based inhibitors, rules out carbon steel in the loop and keeps stainless steel away from the power supply to avoid galvanic corrosion with aluminium, and asks for quarterly pH and conductivity checks and a full water change at least once a year. [3]

Editorial calculation: 75–105 °F is about 24–41 °C and 30–70 psig about 2.1–4.8 bar gauge.

Give the supplier the heat load of the power supply and coils, the flow and pressure each circuit needs, the inlet temperature window, the metals in the equipment's water circuits, the raw water or cooling-tower water available and its summer temperature, and the space for the skid.

02

Open, closed or modified closed loop, and the exchanger that separates it from raw water

Ajax Tocco states that open loops expose the water to air in the reservoir, bringing oxygen to ferrous parts and losing water by evaporation, so for induction systems it uses them only as a secondary circuit where a heat exchanger is already in place; in a closed loop the water does not meet air and keeps its quality. It lists plate-exchanger systems, shell-and-tube systems in which raw water never contacts the system water, closed tank systems with a plate exchanger and a large reservoir for thermal expansion, and side-mount systems fixed to the power supply with a tank, sight gauge, low-level sensor, stainless pump and stainless plate exchanger. [1] [2]

Ajax Tocco describes a plate exchanger as embossed plates bolted in a frame with gaskets, the number of plates set by the cooling needed, taking less floor space than shell-and-tube, easy to clean and easy to extend, and states that it can be three or more times as efficient as a conventional shell-and-tube exchanger. [2]

Hengyang lists a closed cooling tower for its induction melting furnaces, in which pure water or another working fluid runs through a copper coil while spray water outside it carries the heat away, without a cooling pond. [4] Editorial note: with a closed cooling tower, the summer wet-bulb temperature at the site decides whether the loop can stay inside the 75–105 °F window Ajax Tocco gives; ask the supplier for the approach temperature at your design day.

03

Send the heat load, water limits and raw-water source together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Load: [kW from power supply; kW from coils]
Circuits: [flow; pressure; inlet temperature window]
Water: [fill water; conductivity; hardness; pH; glycol]
Metals: [aluminium; copper; brass; stainless]
Rejection: [plant water; cooling tower; closed tower; dry cooler]
Skid: [pumps duty/standby; tank; space]

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