Two Formulas for Combinations of Restrictors

LIQUID FLOW – COMBINATIONS OF RESTRICTIONS

For parallel flow, the total Lohm rating is:

Please note that this relationship is identical to the electrical equation.

Example: Parallel flow

For series flow, the total Lohm rating is:

LIQUID FLOW – SERIES FLOW

One of the reasons for using two restrictors in series is to allow fine-tuning of a total resistance value. If L₁ is known and is more than 90% of L_T, then L₂ may vary by ±5% without altering the value of L_T by more than ±1%, even though the value of L₂ may be as high as 40% of L_T. This effect becomes even more pronounced as L₁ approaches L_T.

To determine the intermediate pressure between two restrictors in series, the following formulas may be used.