MTS Water Quality Guide - Manual (Page 16)

Heat Exchanger Care and Water Quality Guide 16 Heat Exchanger Care
Monitor the cooling
water flow rate
The easiest way to prevent fouling is by assuring that there is a sufficient flow of
cooling water in all of the chambers. This will maintain a “self-cleaning” effect
in the chambers, which also helps them retain their heat transfer characteristics. If
you notice a decrease in the efficiency of your heat exchanger, inspect the filter
or strainer and the chambers for signs of fouling.
When there is a possibility of cooling water surge pressures above the design
pressure of the heat exchanger, a pressure relief or regulating valve should be
installed to protect the exchanger from bursting pressures.
Protect your heat
exchanger during
shipping or storage
To prevent corrosion during shipment and short-term storage, MTS flushes the
chambers with Dow Chemical's Dowfrost HD antifreeze (propylene glycol) after
testing the HPU and preparing it for shipment. Dowfrost HD is a heat transfer
fluid designed to be used in closed loop HVAC systems. It has excellent anti-
corrosion properties and is low in toxicity. The HD signifies that this Dowfrost is
designed to work with the different metals in heat exchangers. MTS warns
against using flushing solutions of ethylene glycol, which can be very corrosive
under certain conditions.
If your heat exchanger is to be shut down or stored for a period of time (weeks or
months) MTS recommends that you drain the heat exchanger and flush it with a
corrosion-preventive fluid to prevent corrosion. Keep the heat exchanger ports
sealed to prevent the entry of dirt or other foreign matter. The heat exchanger
should always be drained when the ambient temperature is less than 32°F (0°C)
to prevent freezing of the cooling fluid and damage to the components.
What regular heat exchanger maintenance is required?
To maintain the life of your heat exchanger, you must service it periodically. The
frequency in which you clean your heat exchanger internally and externally,
depends on the nature of its operating environment and how rapidly it will foul.
Before you use the
heat exchanger for the
first time
Upon receipt of your HPU, MTS recommends that you inspect the heat
exchanger thoroughly, making sure that no dirt or foreign matter entered the unit
during shipment. Check the bolts on the heat exchanger and tighten them if
necessary. The heat exchanger should be mounted solidly in place.
For all types of heat
exchangers
Regular inspection of your heat exchanger will help you identify any decrease in
the efficiency of your heat exchanger. In addition to regular inspections, MTS
recommends that you follow these guidelines:
• Keep a log of data to monitor changes in temperature and pressure.
Collecting and comparing performance data at regular intervals will help
you identify any loss of efficiency and determine the proper interval
required between cleanings.
A loss of efficiency can usually be traced to an accumulation of water scale.
MTS has designed your HPU to provide a fluid velocity of 0.6–1.8 m/s (2-6
ft/s) through the heat exchanger. This flow rate is normally sufficient to keep
a heat exchanger relatively clean.
• Inspect the hydraulic fluid and cooling water often for signs of
contamination. Hydraulic fluid that has water in it will appear cloudy.