De-Ionized Water is being required in chillers at an increasing rate. Today, De-ionized (Dl) Water has become an essential ingredient in hundreds of applications including medical, laboratory, pharmaceutical, cosmetics, electronics, manufacturing, food processing, plating, countless industrial processes, and even the final rinse at the local car wash. However, many people are not aware of the purpose of proper handling of deionized water. It all comes down to chemistry. Deionized water is exactly what it sounds like, water without free ions floating around in it. Why is this important? The free ions present in normal water make it more chemically reactive. Many chillers and heat exchangers use Copper and or Brass components and fittings. These metals are considered “reactive metals” as they have ions that can easily be “stolen” from compounds in contact with them, like water. The water acts as a catalyst stripping ions from the metals. If this goes on long enough the metals are eventually etched away creating leaks, pressure loss, and serious problems for any chiller.
To safely run De-ionized Water it must be used in plumbing materials that are less reactive or entirely non-reactive. The materials we turn to are Stainless Steel which is highly non-reactive and plastic which is inert.
For chillers tasked with running DI water, the fluid circuit should be made from Stainless Steel pure grades like 316L and plastics. For hoses, Rubber, Synthetic Rubbers, or Teflon should be used. This entails changing all of the plumbing materials and components in contact with the fluid circuit. For our chillers and heat exchangers three key chiller components must change, the evaporator, bypass valve, and pump. These are all available in either Stainless Steel or plastic versions.
In the case of the evaporator, the plates are Stainless Steel and the brazing changes from Copper to Nickle. So now the chiller is made from the proper non-reactive materials we can look at the rest of the situation, this means maintaining the deionized water.
Deionized water will not remain deionized forever, even in non-reactive plumbing circuits. The level of deionization will slowly decrease. This necessitates some means of bringing the water’s level of ionization down. For this reason, BV Thermal Systems offers 2 options related to deionization.
1) Filter cartridges with replaceable media/filters
2) DI level measurement
a)Full-featured controller/monitors which constantly monitor and maintain the level of deionization in the water.
b)For low levels of DI filter cartridge mounted indicators show a good or bad LED based on the water’s DI concentration.
So in review, to successfully run Deionized water your chiller must be constructed of the right materials, you need a means of maintaining the level of deionization and a means of reading the ion level. Ask your sales engineer and they will be happy to assist!