Monday, April 2, 2012

Chemical Injection Pumps

A chemical injection pump, or chemical feed pump, is a device used to dispense chemicals into a water system. It is usually made from durable materials like stainless steel and cast iron to withstand chemical wear and tear. There are three basic types, named according to the pump’s mechanism of drawing fluid: centrifugal, metering, and positive displacement.

•    Centrifugal Pump is the most common type and is typically used for large fluid discharge through smaller heads. It is called as such because it uses a rotating impeller to generate velocity and increase fluid pressure and flow rate. The fluid enters the impeller near or along the rotating axis. It is then accelerated by the impeller until fluids are pushed to an outlet, before it exits downstream into a piping. The velocity of liquid being pumped is converted into pressure.

•    A Metering Pump is used to draw a wide variety of chemical agents in precise, adjustable flow rates. Pumped fluid is drawn into a chamber, closing the inlet valve and releasing the fluid afterwards through an outlet valve. Pumps of this type usually have a pump head and a motor. It can also be adjusted either manually or automatically.

•    A Positive Displacement Pump causes fluid movement by trapping a fixed amount of fluid before forcing it into the discharge pipe. It uses rollers, gears, or impellers to move fluid into a fixed cavity, so that the vacuum created through the exiting liquid can draw in more fluid. Volume remains constant in each cycle of operation.

A positive displacement pump is considered a constant flow machine because in theory, it produces the same flow in a given speed whatever the discharge pressure is. In reality, however, true constant flow rate cannot be achieved because there is a slight increase in internal leakage as the pressure increases.

Chemical injection pumps are the most effective but cost-efficient way to treat water problems. Depending of the type of chemical used, several problems can be targeted in a single treatment like bacterial contamination, low pH level, and ion saturation. Furthermore, they are easy to install and operate. They are found in lots of application like chemical manufacturing, oil and gas production, cryogenesis, automotive production, pulp and paper manufacturing, and food production.

Chemical feed pumps use various sources of energy like AC/DC voltage, hydraulic or pneumatic systems, gasoline or diesel engines, steam, water, or natural gas.  Each type is operated depending on its specific fluid handling requirements it will work on like the chemical agent to be used, ambient temperature, and fluid pressure.