GLYCOL CORRECTION FACTORS AND FREEZE PROTECTION TABLES:
PROPYLENE GLYCOL FREEZE AND BURST PROTECTION
PROPYLENE GLYCOL HEAT AND FLOW CORRECTION
PROPYLENE GLYCOL PRESSURE DROP CORRECTION
Freeze Protection (% by volume)
Burst Protection (% by volume)
% By Volume
Heat Transfer
Pump Flow 1.013 1.022 1.032 1.045 1.059 1.077 1.096 1.120 1.145
% By Volume
140°F Solution
100°F Solution
Temp (°F)
20 10
18% 29% 36% 42% 46% 50% 54% 57% 60%
12% 20% 24% 28% 30% 33% 35% 35% 35%
20% 0.987 25% 0.978 30% 0.969 35% 0.957 40% 0.944 45% 0.928 50% 0.912 55% 0.893 60% 0.873
20% 1.067 25% 1.078 30% 1.089 35% 1.106 40% 1.122 45% 1.139 50% 1.156 55% 1.172 60% 1.189
1.098 1.120 1.141 1.168 1.196 1.228 1.261 1.293 1.326
0
-10 -20 -30 -40 -50 -60
NOTES: 1. GARN® recommends the use of Propylene glycol because it is not as toxic as Ethylene glycol. Check with the chemical manufacturer for specific concentration requirements. 2. The “Heat Transfer” correction factors represent the decrease in heat transfer when compared with 100% water and no change in flow rate. The “Pump Flow” correction factors represent the increase in flow required to maintain the same heat output rate as 100% water. 3. The “Pressure Drop” correction factors represent the increase in pressure drop of the system due to the glycol solution as compared to water at the same temperature. EXAMPLE: Select a propylene glycol solution for freeze protection of a coil designed for use as an outdoor air heating coil in Portland, ME. The ASHRAE design heating dry bulb temperature in Portland, ME is -1°F. By using the above table, a glycol solution of 36% is required for freeze protection. EXAMPLE: Let’s say, t he outdoor air coil in the previous example is rated for 50,000 BTUH at 140°F EWT, 20° Δ T, 5 GPM . What is the coil’s rated output with a 36% propylene glycol solution? What increase in GPM is required to maintain the 50,000 BTUH heat output rate? What increase in pressure drop will the pump see?
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Hydronic System Design Manual ©DECTRA CORPORATION - March 2013
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