Smith Precision Products
1299 Lawrence Drive
Newbury Park, CA 91320

Phone: (805) 498-6616
Fax: (805) 499-2867
Product SelectionFebruary 28 2017

Propane & Butane

To determine the actual transfer rate and horsepower required for a selected model pump, the variables shown and described to the left and page bottom may be placed into each performance formula box.

Please click here for help in using our formula calculator.

Two variables that must always be manually keyed into the boxes of the performance formulae are Actual Drive Speed, Nd, and the Differential Pressure, Pd. All other variables may be either hand-typed into the formula, or for best accuracy follow the directions below.

  1. Select a pump model in the table provided and click on the rated transfer capacity of the pump, Qr. This value will be automatically transferred into the performance formulae box for Qr.
  2. Next, click on the rated speed of that particular pump model, Nr, as shown in the table and this value will be transferred.
  3. Then, select the slippage factor, Fs, to be used at the bottom of this page. Click on the slippage factor required and it will be automatically placed into the performance formulae box.
  4. For liquids/liquefied gases that we do not provide a slippage factor for, use the Slippage Factor Graph to determine Fs and manually key into the Fs box provided with the performance formulae.

Once all variables are located in the performance formulae boxes, click on the Calculate GPM box and the expected transfer rate is shown. Then, click on the Calculate Horsepower box and the answer is shown.

Smith performance formulae give a very accurate representation of field performance of a selected pump model due to the viscosity changes of the fluid being transferred at various temperatures. A performance curve can easily be drafted by determining the flow rate and horsepower requirement at three different differential pressure points, such curve showing the expected flow rate and horsepower at the differential pressure required.

For Propane/Butane pumps, performance curves are published in Catalogue CP-3, available for download from this site.

For inlet line recommendations, download Manual AL-3

Roll Over a Variable Below to View Its Definition

Actual Pump Delivery in U.S. Gallons Per Minute Rated Transfer Capacity in GPM Differential Pressure Being Pumped Against, in Pounds Per Square Inch Horsepower Required To Drive Pump Actual Speed of Pump Shaft in RPM Rated Speed of Pump Shaft Slippage Factor, A Variable Depending on the Viscosity of the Fluid Pumped

Model Rated Transfer Capacity (GPM) Rated Shaft Speed (RPM)

Slippage Factor, Fs

  +100°F +80°F +60°F +40°F +20°F 0°F -20°F -40°F
Butane 0.0033 0.0032 0.0031 0.0028        
Propane 0.0042 0.0040 0.0038 0.0036 0.0034 0.0033 0.0032