The Lohm has been selected so that a 1 Lohm restriction will permit a flow of 100 gallons per minute of water with a pressure drop of 25 psi at a temperature of 80°F.
Where:
I = Flow rate (gallons per minute)
H = Differential pressure (psi)
L = Lohm rate, a measure of resistance to liquid flow. It includes all density, viscosity, Reynolds number, coefficient of discharge, and area units (Lohms).
When testing on water at 25 psi, ∆P, √H = 5 and the above formulas simplify as follows:
and
Some useful relationships:
Example 1. What restriction will permit a flow of 1 gallon of water per hour at 50 psi ∆P?
I = 1/60 = 0.0167 GPM
Example 2. A jet with an approximate hole diameter of 0.012 of an inch flows 18 lb/hr of water at 100 psi ∆P. What is the restriction?
Example 3. What ∆P will be required to flow 20 GPH of water through a 2000 Lohm Jet?
Example 4. What water flow will result from a restriction of 500 Lohms and a ∆P of 500 psi?
NOTE:
For special flow requirements, contact your local Lee Sales Engineer to determine the required Lohm rating.
Always verify flow calculations by experiment.
*There are many parameters to consider when determining V-Factor. Click here for more information.