Fluids with differing viscosities or specific gravities need to be corrected to water, to obtain accurate performance estimates.
The performance specifications for Jacoby-Tarbox eductor eductors are based on using water with a specific gravity of 1.0 and a viscosity of 1 Centipoise.
In all cases, the correct unit is the one that matches your desired range of motive-to-suction flows the closest.Ĭorrecting for Non-Water Fluid Specifications
As a general rule in dilution applications, the HL is the best unit to choose. In this case, the motive flow should be matched to the desired motive flow and the suction port should be throttled to achieve the desired dilution rate. In other applications, such as the dilution of chemicals, the motive flow should be as high as possible: while the suction flow will be low. This is generally true for pumping applications. In some cases, the unit chosen will have the greatest suction flow while consuming as little motive fluid as possible. If a turndown ratio*** of greater than 35% is needed, then choose two or more eductors that have the correct turndown ratio and operate these units in parallel. Select the unit from Steps 1-4 that best meets the motive and suction parameters of the specific application. Do this for each of the models of eductors. If an exact match is desired, consult your Jerguson/Jacoby-Tarbox representative.Ĭalculate the amount of motive flow used by multiplying the Q," and Qs found in the tables by the Tabulated S.E obtained in Step 3. If a standard unit is being used, pick the size unit that has a Tabulated S.E equal to or greater than the Desired S.F. To determine the size of eductor needed, first use the following formula to determine the Desired Sizing Factor (S.F.) Do this for each of the models. The flow specified represents the Tabulated Suction Flow for each of the different models of eductors. (Be certain that friction losses in the outlet line are calculated using the combined rate of both the motive and the suction flows.) It is important that the outlet line from the eductor be as large or larger than the outlet connection.įind the motive pressure (Pm)' Locate the motive pressure from the table that is closest to or lower than your actual motive pressure. It is important to include friction losses into the desired outlet head. Using the NPSH number will correct for temperature variations and friction losses, resulting in a more accurate value.įind the outlet head** (Ho) equal to or greater than your actual outlet head. You can also or use the calculated result from the NPSH formula found on page 5 of this manual. If your lift is between two of the lifts on the table, use an average of the two. (NOTE: All Jacoby-Tarbox eductor tables use the 1-1/2 inch unit as the standard, and eductors are sized using a Sizing Factor (S.E) based on this standard unit.)įind the suction lift* or head (Hs) that is equal to or greater than your desired lift. To determine the correct eductor for a specific application, follow the steps in this section, using the performance tables provided to achieve your desired results. Using Liquid Motives to Pump Liquid Suction Fluids
How to Size Liquid Motive Eductors for Pumping Liquids