Home > Resource Center > Engineering Data > Lohm Laws for Liquids Lohm Laws for Liquids – Examples of How to Calculate Flow Resistance for Liquids Liquid Flow - Examples Problem 1. A restrictor required to flow 0.1 GPM of 50/50 ethylene glycol/water blend at 45°F and 6 psid. How many Lohms are required? Solution: 1. Read specific gravity; S= 1.07 from curve. 2. Read kinematic viscosity; n = 5.0 cs from curve. 3. Use n and DP to determine viscosity correction factor, V=.87, from curve. 4. Select unit constant K from table. 5. Compute Lohms required. Problem 2. What pressure drop will result for a flow of 57 mL/min. of 50/50 ethylene glycol/water mixture at 45°F, flowing through a 1000 Lohm restrictor? Solution: 1. Find specific gravity and viscosity: S = 1.07, v = 5 cs 2. Use knowledge of system to assume initial solution. H = 4 psid 3. Use assumed H to determine V = 0.75 from curve. 4. Select units constant K from table. 5. Compute trial DP: 6. Make trials as required to find correct solution. H = 2 psid V = .55
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