Quarterly Preventive Maintenance Testing
As part of a preventive maintenance program, the glycol concentration should be tested on a quarterly basis. Either ethylene glycol or propylene glycol is used in HVAC closed loops. Ethylene glycol is most commonly used in HVAC applications due to its lower cost, lower viscosity, and better heat transfer properties.
A specially calibrated refractometer is a reliable way to determine the concentration of glycol. By putting a sample of the glycol mixture on a slide, and then looking through the refractometer, it will indicate the refraction of light reading, showing a measurement between 32°F to -60°F. When selecting a glycol concentration based on your desired freeze protection, the freeze point should be at least 5°F below your lowest anticipated exposed temperature. In the Washington DC metro area, the target reading should be around -20°F. Glycol solutions should be sampled and submitted for laboratory testing annually to determine the concentration, pH, reserve alkalinity, inhibitor levels and sediment content.
Additional Factors to Consider in Glycol Testing
Although this test seems simple, there are other variables that need to be taken into consideration that require technical expertise from a commercial HVAC contractor, including the following.
- An understanding of the water quality used and the water guidelines to follow.
- Knowledge of the manufacturer’s specification for each type of equipment as systems can require concentrations anywhere from 20% -100%.
- Calculating the dilution of glycol to water ratio (if maintenance was performed on the system)
- Total system volume for each piece of equipment
- What other systems are related to the glycol system
- Type of glycol to use
- Knowledge of glycol degradation and treatment measures
Recent Example of Air Cooled Chiller PM
CFSI recently was awarded a preventive maintenance agreement for a site that utilizes a 100+ ton air cooled chiller. Since this was a new customer, we ran a full spectrum analysis of the liquid in the system using Dow Chemical’s lab that tests for 21 items, including appearance, concentration, freeze point, chemical properties, corrosion inhibitors, corrosives and scale promoters, and contaminants and other glycols.
The finding indicated the condition of the fluid was outside the recommended ranges and the glycol strength was below the minimum recommended concentrations because the fluid was over-diluted. The recorded freeze protection was at 18°. If not caught, the system could have suffered a catastrophic freeze during winter, causing hundreds of thousands of dollars worth of damage. Also, the fluid had a cloudy appearance with suspended solids that could be detrimental to mechanical pump seals and would over time lead to heat exchanger fouling and even leaks from corrosion. CFSI service technicians were able to restore the glycol concentration to the recommended range, preventing the pipes from freezing and further corrosion.
Call Crockett Facilities Services Now to Avoid Problems in the Winter Time
Plan ahead and save headaches and costs down the road. Call Crockett Facilities Services now to schedule a service call to test your glycol concentrations. Your HVAC closed loop systems that contain a high-quality, properly inhibited glycol solution will give you years of low operating maintenance. An ounce of prevention is worth a pound of cure!
Call 202.600.2787, email sales@crockett-facilities.com or complete our online form for a service quote. Crockett Facilities Services Inc., a top ten mechanical contractor, provides 24/7 commercial HVAC and mechanical services throughout Washington D.C., Maryland, and Virginia.