FIRST QUARTER 2019 13 continued on page 14 from your steam system and analyze them in order to set up the proper dosing schedule to maintain proper boiler chemistry. Water testing should be done every few months at a minimum. If you own a water softener instead of using a service, most large swimming pool supply houses will be able to test for hardness often at no charge. Now that you’re aware boilers need the proper water chemistry and there are effective means to treat the water in order to provide the proper chemistry, what could go wrong? Plenty, and the next section will suggest how to avoid problems. PITFALLS OF WATER BOILER TREATMENT Here are two common situations found in makeup water that you are able to control: Dissolved Oxygen: Oxygen dissolved in feedwater attacks the steel in the boiler and the feedwater system and causes a condition described as "pitting." The pits produced can vary from tiny depressions to holes large enough to penetrate the boiler metal and are usually covered with pimple-like bumps of rust. Once pitting starts, it may be extremely hard to arrest and can proceed at a rapid rate. Sodium sulfite is used to remove the dissolved oxygen left in the feedwater. It reacts chemically with dissolved oxygen, binding it to stop it from destroying metal. Dissolved oxygen control is based on maintaining a level of sodium sulfite in the boiler water. It’s important that the feedwater and make up water are mixed thoroughly and as quickly as possible so that sodium sulfite binds feedwater oxygen before the oxygen can cause damage to the boiler. With this in mind it is far better to add compound to the return tank using a metering pump when new makeup water is added to the return tank or when the return pump is pumping water into the boiler than it is to add the compound manually a couple of times a day. When water is heated, the dissolved oxygen is driven off. Then, the condensed steam (condensate) flowing back to the condensate return tank is essentially oxygen free. Only new, untreated make up (city) water adds the damaging oxygen. Constant addition of new water caused continued from page 12 FE ATURE