GSI Group - Laser Division
JK300HP/JK300P/JK125P
Pre-installation and User Manual
Issue 2.0
Page 42 of 172
Part No: 1EA300E01
steel, copper, copper alloys and aluminium. One suitable corrosion inhibitor is Sodium
Nitrite (NaNO
2
) as supplied by a reputable water treatment supplier.
The quantity of corrosion inhibitor requires to be determined by chemical analysis of the
water to give a dosage as recommended by the corrosion inhibitor supplier (a typical dosage
is approximately 1000 parts per million). Actual dosage is dependent on the volume of water
in the cooling system.
Protection of the system cannot be ensured unless the level of corrosion inhibitor is regularly
monitored. Hardness stabilisers may also be required to ensure hardness levels and pH
levels are maintained within the prescribed limits (see requirements stated above).
Biocides
The external cooling water shall also include an active biocide to prevent fouling, leakage
and corrosion. Temperatures that are generally encountered in the external cooling water
are ideal for sustaining bacterial growth. A broad-spectrum biocide (e.g. Isothiazolone) must
be introduced at levels recommended by the biocide manufacturer. Monitoring and
adjustment of the biocide dosage must be made every three months. Refer to a reputable
water treatment supplier.
Freeze Prevention
Mechanical means must be provided to prevent freezing, e.g. electrical heaters. The use of
Ethylene Glycol and other similar agents is not recommended. Anti-freeze additives have
inherent corrosive properties and are nutrients for a wide range of bacterial contamination.
If anti-freeze additives are used, then the User must understand that the adding of anti-
freeze will reduce the thermal capacity of the coolant. Typically it will be necessary to reduce
the coolant temperature by a few degrees to compensate for the lower thermal capacity – in
extreme cases this may require the capacity of the chiller to be increased.
Dehumidification/Chiller bypass
The JK300HP/JK300P/JK125P Series Laser is fitted with an internal condenser that
maintains the air within the cabinet at a low dew point to prevent condensation on the
pumping chambers or other cooled surfaces. This condenser is fed from the external water
supply at a constant rate independently of the cooler control valve. This provides a
permanent bypass at all times so that chiller flow will be maintained even when the laser is
switched off.
3.3.2.2 Internal Cooling Water Requirements
Pumping chamber circulating water shall be low in inorganic, organic or colloidal
contaminants, conforming to ISO 3696 (EN ISO 3696) Grade 3 but with an improved
conductivity. 10 litres (2.64 US gallons) are required for the installation of the
JK300HP/JK300P/JK125P laser. This type of water is often referred to as de-mineralised
water being produced by distillation, de-ionisation or by reverse osmosis. This water has the
following basic requirements:
pH value at 25 °C
5.0 to 7.5 inclusive
Electrical conductivity at 25 °C
0.1mS/m max
Oxidizable matter Oxygen (O) content
0.4mg/L max
Residue on evaporation at 110 °C
2mg/kg max
Petitioners Canadian Solar Inc. and Canadian Solar (USA) Inc.
Ex. 1025, p. 42
