Elkhart offers an eductor for all handlines (1” through 2-1/2”) and the educators are compatible with most foam concentrates.
Elkhart 241-30 Foam Eductor, 1" NH Female X 1"
All Elkhart’s eductors:
- Are easy hook-up / easy set-up
- Feature red urethane enamel finish
- Can be deployed in any position
- Offer a removable pick-up screen and removable metering valve
- Comes with a clear PVC pick-up hose
is a device that uses the Venturi principle to introduce a proportionate amount of liquid concentrate into a water stream. The venturi is the constricted portion of the waterway near the educator inlet. This restricted passage increases water velocity, this momentarily reducing its pressure as it passes into the larger area of the induction chamber. Concentrate is introduced into this reduced pressure area through a metering device. The venture orifice performs as a very efficient straight bore nozzle that is calibrated for a given flow at a given pressure.
Elkhart eductors are calibrated to flow rated capacity at 200 p.s.i. inlet pressure and most non-aspirating fog/straight stream nozzles achieve rated flow at 100 p.s.i. Eductor inlet pressure of 200 p.s.i. is necessary to overcome significant friction loss through the venture and additional friction loss between the eductor and the nozzle. The nozzle must match the flow rate of the eductor.
The eductor controls the flow through the entire system. If inlet pressure is increased, the flow of water will increase and if inlet pressure is decreased, the flow of water will decrease. As long as 200 p.s.i. inlet pressure
is maintained, the eductor will flow rated capacity,
even with different nozzles and hose lays (even with no hose or nozzle connected to the eductor outlet.) The exception is if the nozzle has a lesser rated flow than the eductor. The nozzle will then take over control of the entire system and the eductor will not function properly. Once the eductor has established the flow of water, the performance of the downstream portion of the system will be determined by that flow. Friction loss through the eductor is not fixed.
Friction loss through the eductor can be calculated by subtracting the following three factors from the inlet pressure; (a) nozzle pressure, (b) hose friction loss between the eductor and the nozzle, (c) any pressure change due to a difference in elevation between the eductor and the nozzle. The eductor will pick up concentrate whenever the outlet pressure is less than 65% of the inlet pressure.
A metering device
controls the flow of concentrate into the eductor. Atmospheric pressure acting on the surface of the foam concentrate, in its container, pushes the concentrate into the pick-up tube, through the metering device and into the reduced pressure induction chamber. Atmospheric pressure does not change,
so the flow of concentrate remains the same as long as the low pressure area is created. However, the flow of water will be different at different inlet pressures. Since the flow of concentrate remains the same but the flow of water changes, the resulting solution will have different percentages of concentrate at different inlet pressures.
The percentage shown on the metering device only applies at the correct eductor inlet pressure (200 p.s.i.). If the eductor is operated at less than 200 p.s.i. inlet pressure
and thus a lower flow of water
through the unit, the resulting foam solution will have a higher percentage of concentrate.
With inlet pressure higher than 200 p.s.i.
the foam solution will have a lower percentage of concentrate.
Elkhart educators are available in flow rates of 30, 60, 95, 125 and 250 g.p.m.
and are designed to give the lowest possible pressure drop through the venturi and the most efficient recovery of pressure downstream.