What is a micro-injection pump?

It is a precision metering pump that can inject volumes as low as 0.025 cc/stroke into a given process at pressures up to 8000 psig, (552 barg). Due to the unique design of a Williams Series V, micro-injection pump it has the ability to adjust the volume per stroke as well as the number of strokes per minute on the pump while operating.


How do micro-injection pumps work?


Williams pumps are pneumatically actuated injection pumps that consist of an Oscillamatic controller (timer) which generates pulses of air that are introduced into the pneumatic portion of the pump. The air from the Controller pushes down on the piston of the pump, which moves the plunger down into the fluid cylinder, this is called the “power stroke”. This displaces chemical in the fluid chamber, seats the suction check valve, and generates pressure to exit chemical out the discharge check valve. Then the Oscillamatic Controller enters the exhaust cycle and the air is removed from the top of the piston/plunger assembly and the pump returns to what is referred to as the “suction stroke”.Then the whole process continues again and again until the air is shut off to the Oscillamatic Controller.

Williams Micro-Injection Pumps - CP125V125CRTC Pump

Diagram of a Williams CP125V125CRTC Pump


When would you use a micro-injection pump?


When you need to use “Neat or concentrated” chemicals into a process and don't want to rely on diluted chemical injection because the current pump can’t turn down low enough to do micro-injection.

What is a neat chemical?

Neat chemicals are concentrated chemicals that require a much smaller dose to be injected into the application. Because of the concentration, neat chemicals take up less space to store and weigh less when shipping. Using a pump that can accurately micro-inject small concentrated amounts of chemical into an application with precise turndown is a requirement.


What are the benefits and advantages?


Second to manpower, chemicals are one of the highest overhead costs in a process.. Therefore using the right amount of chemical and optimizing the dosage can be one of the keys to lowering the overall costs associated with many processes. The ability to inject the right amount of chemical versus overdosing can not only reduce costs but reduce undesirable results


Are there limitations or disadvantages on micro-injection?


The standard product comes with manual adjustment, done locally and must be changed if the process flow increases or decreases between calibrations or settings. All of the Williams Micro-Injection pumps can be automated with the addition of a pump control unit that when connected to a flow signal will slow down or speed up the number of strokes per minute which will reduce or increase the volume of injection the pump produces


What industries and or applications use this type of pump?


Applications for this pump can be found in a range of applications including petrochemical plants, refineries, offshore platforms, corrosion Inhibitors, scale inhibitors, de-foamers, mercaptans, trace additives and many more.

Micro-Injection System

Example of a Series V, Micro-injection System


What is the life of this type of pump?


The Williams Micro-Injection pump is designed and manufactured using 316 stainless steel with the product life expectancy up to 30 years with recommended maintenance. Williams pumps are designed to withstand some of the harshest conditions and environments and still perform incredibly well for many years.

Series V, Micro-Injection Pump, Model CP125V125

Series V, Micro-Injection Pump, Model CP125V125


Are there price considerations? What is the cost of ownership?


There are several options when selecting the micro-injection pump which will lower the overall cost of ownership throughout the life of the pump.

  • Selecting the right plunger material and seal combination can result in longer times between maintenance and therefore reduce downtime and labor costs related to unplanned maintenance and possible disruption of the process..
  • Optional ceramic plungers can be compared to the hardness of a sapphire and a diamond and therefore won’t scratch or wear quickly so the seals last longer before needing to be replaced.
  • Meets API 675 standards