Advantages of CSI pumped venturi metering pumps vs piston and diaphragm pumps
| CSI pumped venturi metering pumps | Most piston and diaphragm metering pumps |
|---|---|
| Simple flow rate adjustment: No need to stop the metering pump. Adjust the metering valve and immediately see the effect of the adjustment on the built-in flowmeter. |
Complex flow rate adjustment: Stop the metering pump. Change stroke length. Calibrate. Repeat the procedure until you get it right. |
| Foolproof calibration: Built-in flowmeter provides continuous flow rate information. |
Tiresome calibration procedure: The only way to check flow rate is by timing the emptying of a calibrated cylinder with a stopwatch. |
| Excellent accuracy and repeatability: Pumped venturi injects at constant rate over its whole operating pressure range. |
Flow varies with line pressure: Flow rate fluctuates when pipeline pressure changes, due to diaphragm flexing and/or ball-check seating. |
| Smooth flow: Venturi draws injected fluid into the water stream smoothly, continuously. |
Pulsing flow: Flow starts and stops with each stroke of the pump. |
| No backpressure valve needed: All required flow devices are included with the metering pump. |
Backpressure valve adds cost: Injection quill backpressure valve adds to initial cost and adds another component that needs maintenance. |
| Excellent dispersion: Injected materials go through 2 stages of smooth dispersion, the first stage at the venturi and the second stage when the liquid enters the main pipeline. |
Poor dispersion: Concentrated material goes directly into the main pipeline without pre-dilution. Even centerline quills cannot change the pulsating nature of the injection. |
| Simple mechanism: Water from the centrifugal pump drives a venturi. No gears, diaphragms or pistons. Only one wearing part: the centrifugal pump seal. No lubrication needed. |
Complex mechanism: Reciprocating motion has many more moving parts. Oil fill and/or lube points are needed. Repairs require a skilled mechanic. |
| No contact between pump and the injected chemicals: Injected liquid enters the water stream at the venturi -- DOWNSTREAM of all moving parts. |
Whole pump is in contact with injected chemicals: All wetted pump components are in continuous contact with injected chemicals. |
| Greater safety: Concentrated chemical is under vacuum. Leaks are less likely, and they are less hazardous if they do occur. |
Less safety: Concentrated chemical is under high pressure between the pump and the pipeline. It can spray out from any leak. |
| Wide capacity range: Single venturi metering pump models allow injection rates from 1 gph to 400 gph. Special designs are available for even higher flows. |
Narrower capacity range: Most piston pumps are limited to flows of 200 gph or less. |
| Excellent turn-down: CSI offers configurations where minimum repeatable flow can be less than 1% of maximum flow. |
Delivery problems at low flow: Accuracy/repeatability of most piston and diaphragm pumps deteriorates badly at flow less than 10% of capacity. |
| Injecting multiple chemicals is easy: Several venturis can be installed in parallel on one centrifugal pump. CSI models are available for smooth simultaneous injection of 1, 2, 3 or 4 chemicals. |
Injecting multiple chemicals is difficult: Some suppliers offer dual head pumps, but these suffer all the same disadvantages as their single-head pumps. |
| More power options: In addition to providing metering pumps for any country's electrical characteristics, CSI offers gasoline, diesel and hydraulic powered versions of most metering pump models. |
Few power options: Only a few piston and diaphragm pump manufacturers offer anything other than electric motors. |
| Do it your way: CSI offers you more capacity choices, more simultaneous metering choices, more power choices and more system capabilities than any other metering pump supplier. |
Why do it their way? |
For answers to your questions about pumped venturi metering pumps or systems based on this technology contact Chemigation Systems International.