Recommended Boiler Water Tests

Boilers play a crucial role in many industrial and commercial applications. Steam is used to heat buildings, manufacture products, process food, sterilize instruments, drive chemical reactions, generate electricity and many more applications. Regular boiler water testing is necessary to ensure optimum performance for this essential piece of equipment.

Boilers vary greatly in design, size, steam output and pressures. Very small boilers may be heating a school, pressing clothes in a dry cleaner or sanitizing surfaces in a food packing facility. Mid-size units are the mainstay of manufacturing, chemical processers, hospitals and heating systems in large commercial buildings. Utility boilers run electric generators, help make steel and aluminum and refine petroleum.

Why is Boiler Water Testing Necessary?

The quality and quantity of water are critical to boiler operation. The two main problems for boilers under 300 psig are scale and corrosion. Calcium Carbonate scale build-up in the tubes is a super insulator. This build-up of calcium carbonate greatly increases fuel costs by reducing heat transfer to the water. Scale builds up in layers and will reduce the water flow thru the system wasting energy and efficiency. Boiler water testing aims to prevent these issues.

Dissolved oxygen is one of the most notable causes of corrosion in boiler water. Oxygen pitting can occur in the boiler drum, steam lines and condensate return systems. If the temperature is too high, even the smallest amount of dissolved oxygen can cause corrosion. Carbonic acid attack occurs when the steam condenses and the CO2 hydrolyses to form Carbonic acid.

The water treater’s job is to prevent scale and corrosion from happening, so the boiler can run efficiently. With regular boiler tests and water analysis, water treaters can:

Prevent boiler scale
Maintain boiler water’s alkaline condition
Remove dissolved gases
Limit sludge formation
Determine the required amount of treatment
Improve boiler efficiency
Control water treatment chemicals

Preventing Boiler Scale

Boiler scale in systems under 300 psig is almost always Calcium and Magnesium deposition. The hardness ions have an inverse solubility curve — as the water temperature goes up, their solubility goes down.

Water treaters know that good scale control begins with good pretreatment. A zeolite softener will exchange 99% of the Calcium and Magnesium for Sodium, which has extremely high solubility.

In systems with a high percentage of condensate return, the softener is enough. For boiler systems where the returns are under 75 or 80%, though, the water treater may want to propose a reverse osmosis (RO) system for the pretreatment.

The RO unit should remove 96% of all the dissolved ions in the water, greatly increasing the cycles of concentration and reducing blowdown. Blowdown is a key factor in controlling boiler water contaminants to prevent deposition on the water surfaces and carryover with the steam. The higher the cycles, the lower the blowdown.

The next step in scale control is the water treatment program. Boiler water treatment plans can include a series of approaches. Controllers are excellent for monitoring the boiler systems and feeding chemicals by metering pumps. Good control equipment and remote monitoring tools, like cellular modems, are vital to a treatment program and allow the water chemist to monitor the system 24/7. Regular boiler water testing is also critical.

The chemist will decide which method is required and apply it to the system. Your testing program needs to be in sync with the chemistry and be used to verify that the testing program is within the set parameters. Boilers require attention. The water treater, the service technician and the on-site operators must be testing regularly. Failure to properly maintain a boiler system can result in catastrophic failure.

How Often Should Boiler Water Be Tested?

Regular boiler water tests are crucial to ensure that the entire steam system is protected and fully functioning. When possible, the water treater should be testing the make-up water, the softener and/or RO pretreatment systems, the deaerator, the feedwater, the boiler water and the condensate systems. Boiler water tests are based on the program selected by the chemist. All boilers should have OH or P&T Alkalinity, Sulfite or other Oxygen scavenger, Chlorides and Conductivity tested at least once per shift.

If the scale control program is Phosphate or Phosphonate based, test once per shift. Chelant programs should be tested every 4 hours, and all polymer systems should be tested every shift. Testing includes:

Make-up Water: The boiler technician should check the make-up water daily. Key test parameters are hardness, alkalinity and conductivity.
Softener and/or RO unit: Test for hardness and conductivity based on softener capacity and gallons of make-up water. Test every shift if possible when you have reached 75% of softening capacity.
Deaerator: To ensure the unit is functioning properly, it is good practice to run Dissolved Oxygen tests on the deaerator monthly. While testing for O2, an astute water treater will check the temperature and pressure in the unit to be certain they are at manufacturer’s recommended levels.
Feedwater: The feedwater should be tested every shift for sulfite, hardness, chlorides and conductivity (if DEHA or other type of Oxygen scavenger is used test for it in the feedwater).
Condensate: A pH test should be performed every shift — especially if neutralizing amines are used. Conductivity and Iron tests should be performed daily. If the program uses DEHA, then test for it in the condensate every shift. If the new polyamine is being fed, then test the condensate every shift. Iron testing is ideal for early detection of corrosion cells.

Boiler Water Parameters and Limits

When you conduct the recommended boiler water tests, you’ll want to determine whether the results fall within the acceptable parameters. The water treater must set the test parameters based on his knowledge of the mechanical systems, boiler types, the equipment manufacturer’s recommendations and the control rates set by the chemical formulator.

While testing parameters vary, there are some general considerations for various tests:

pH: A boiler pH test kit will give you a number between zero and 14. Seven is neutral, values below seven are acidic and values above are alkaline. Boiler pH should remain between 10.5 and 11.0 to prevent acidic corrosion.
Alkalinity: An alkalinity test will help you determine if your boiler water is within the preferred zone. Hydroxyl Alkalinity is necessary for corrosion control and scale prevention.
Phosphates: A common boiler water test is a phosphate test. Phosphates react with calcium hardness to precipitate it in a controllable form. These levels should generally be between 30 and 50 ppm.

The complexity of boiler systems controls requires a deep understanding of how the systems and the related treatments function. There is no general rule, success is based on knowledge and hard work. Testing is paramount for good operations and the safety of employees!

AquaPhoenix Can Meet Your Boiler Water Test Kit Needs

AquaPhoenix can provide your company with custom test kits to help you determine whether your boiler water meets the applicable quality parameters and help you maintain boiler efficiency. Take advantage of our fast shipping and lack of minimum order requirements along with our industry-best customer service.

Place your order today or contact us for more information about any of our testing products. Learn more about our cooling tower test kits as well!