03 Dec Does the Dosing pump for my application require any Inputs (Is it necessary to control the pump externally via a pulsing contact or a 4-20mA signal?)?
Our first blog in the series (missed it? catch up here) covered the Flow Rate required and Pressure you intend to pump into.
Further to this, all pumps have internal timers which regulate the speed, or frequency at which the pump’s solenoid strokes. The speed is adjusted or programmed on the pump to achieve a constant dose rate. However, if a variable dose rate is required, for example, to dose proportional to water make-up, or to dose proportional to pH or ORP levels in the water, then external input capability is necessary. External inputs can either be in the form of a contact closure (such as from a controller or water flow meter) or a 4-20mA current. If external control is required, or even internal control with extreme turndown facility, it is necessary to select a pump with external control capability.
Besides EMEC’s basic VCO, TCO or KCOPLUS pumps, the rest of the range has external input capability via pulse or 4-20mA. Furthermore, all these pumps have a float on the foot valve so if the chemical tank/drum empties, the dosing pump will stop dosing before it loses prime. This is a very useful feature, because when the chemical drum is replaced with a full one, the pump will not need to be reprimed.
Other questions to ask are: What flow rate do I require and what pressure am I pumping into? What chemical am I dosing? What temperature am I dosing into? Is my preference for pump configuration Foot Mount or Wall Mount?
You can fast track the process and learn the answers to each of these questions by downloading our complete guide here