• 100 ppm of Nalco 77352 (isothiazolone)
The choice of biocide depends on the expected microbiological material in the cooling loop.
Glutaraldehyde biocide is more effective against anaerobic bacteria. Isothiazolone is more
effective against aerobic bacteria, fungi, and algae. When in doubt, use the isothiazolone
biocide.
3) Conrm azole residual using Nalco azole test kit.
If the system was cleaned by using deionized water only and the system is full of deionized water,
complete the following steps:
1) Add one of the following biocides:
• 100 parts per million (ppm) of Nalco H-550 (glutaraldehyde)
• 200 ppm of Nalco 73500 (glutaraldehyde)
• 100 ppm of Nalco 77352 (isothiazolone)
The choice of biocide depends on the expected microbiological material in the cooling loop.
Glutaraldehyde biocide is more effective against anaerobic bacteria. Isothiazolone is more
effective against aerobic bacteria, fungi, and algae. When in doubt, use the isothiazolone
biocide.
2) Add 120 ppm of Nalco 3DT-199 to achieve 40 ppm azole concentration.
3) Conrm azole residual using Nalco azole test kit.
System monitoring and maintenance
Use the following guidelines for system monitoring and maintenance:
• It is important to conduct a bacteria test on a quarterly basis and add 100 ppm of Nalco H-550 or 200
ppm of Nalco 73500 biocide if the bacteria count is greater than 1000 CFU/ml. Nalco 77352 fungicide
can be added if fungi have been a concern in the past.
– Fungi might not be detected in the water, even though it can grow and cause blockage of cooling
channels in cold plates that are used to cool the computer processors. Reduced coolant flow rate
through the cold plates might be an indication of blocked channels due to fungi growth.
• On large systems that have more than 250 gallons of water, Nalco 3D TRASAR
®
controller must be
installed on the system cooling loop to enable precise and continuous monitoring of system water
chemistries, conductivity, pH, corrosion rate, and turbidity.
• It is important to conduct an azole test on an annual basis and add Nalco 3DT-199 to bring the azole
concentration to the wanted 40 ppm level or any other desirable ppm level.
Multiple racks
Use the following guidelines when adding additional racks:
• Racks arrive from IBM ready for installation.
• Install rack or racks and open flow from existing system.
• Make sure that the automated water make up on the chiller coolant reservoir is activated. If there is no
automated water make up feature, top off the system side reservoir.
• Within 2 hours of installing the new rack or racks, add one of the following biocides:
– 100 parts per million (ppm) of Nalco H-550 (glutaraldehyde)
– 200 ppm of Nalco 73500 (glutaraldehyde)
– 100 ppm of Nalco 77352 (isothiazolone)
The choice of biocide depends on the expected microbiological material in the cooling loop.
Glutaraldehyde biocide is more effective against anaerobic bacteria. Isothiazolone is more effective
against aerobic bacteria, fungi, and algae. When in doubt, use the isothiazolone biocide.
Racks and rack features
167
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