At the heart of every Agri-Inject chemigation system is a diaphragm metering pump.
We made the decision to utilize only diaphragm pumps, rather than piston type pumps, many years ago. And the reasons remain as valid today as they were then.
They involve accuracy, reliability, ease of operation, and safety.
The primary difference between the diaphragm pump and the piston pump is simple.
In the diaphragm pump, there are very few moving parts and only a limited portion of the internal area is exposed to the chemical being injected.
A Teflon® diaphragm acts as a barrier between the piston and the process fluid - the liquid fertilizer or chemical being moved. The piston's pumping motion is applied to a hydraulic fluid, causing the diaphragm to flex and move the process fluid.
With the piston pump, the piston and much of the internal area comes into direct contact with the process fluid. The corrosive nature of some of these fluids can result in increased maintenance and reduced useful life of the unit.
The diaphragm style pump is leak-proof, making it safe for handling all types of chemicals. All moving parts are submerged in oil, giving it a longer life with a minimum of maintenance.
In the piston pump, a certain amount of leakage must be expected. The piston requires packing to provide a seal and a small amount of controlled leakage past the packing is commonplace. Friction between the piston and the packing also increases leakage. Piston pumps are not recommended for use with hazardous or toxic chemicals.
On our mRoy diaphragm pumps, the injection rate can be adjusted while the unit is running. Accurate calibration of the pump to minute increments is as simple as turning a dial.
Volume adjustments to the piston style pump require that the pump be stopped, the stroke length of the piston mechanically adjusted, and the pump restarted to check the injection rate. The process is time consuming and frustrating, and often discourages accurate calibration of the unit.
Experience over the years has demonstrated the advantages of the diaphragm pump.