Monthly Archives: March 2016

//March

Sizing your chemical metering pump and determining injection rate (#2 of 8)

This is the second of eight articles in the series Sizing & Selecting the Right Chemical Metering Pump. Read the previous article “Planning for your Application.”

A metering pump is used to inject chemicals precisely into a process to achieve a certain desired result. That result could range from a certain amount by volume or mass of fertilizer to a definite amount of acid into water to achieve a certain pH balance. Or it could even be a certain amount of disinfectant into water to achieve a predetermined amount of PPM (parts per million).

The actual injection rate or the rate at which the chemical needs to be added depends upon the application, desired result and also the concentration of the chemical. For example, in case of the amount of chlorine the formula for calculation of the chemical injection rate is:

IR = 0.006xQxC / S

Where Q – System flow rate in GPM, C – Desired PPM for the chemical and S – Concentration of the chlorine bleach in %

There are many methods to arrive at the desired chemical injection rate and usually engineers will specify the exact rate using such methods based upon the application. Once you know the rate of chemical injection which is usually given in Gallons Per Hour (GPH), you need to then start the process of sizing the pump.

The second most important piece of information is the pressure that the pump needs to overcome to inject the chemical. If you are injecting into a pipe then the chemical pump needs to be able to overcome the pressure in the pipe as well as the pressure drop in the chemical lines from the chemical pump to the injection point. A pump injecting into a pipe […]

By |March 30th, 2016|Metering Pumps Tips, News, Selecting the Right Pump|3 Comments

Planning for Your Chemical Metering Pump’s Application (#1 of 8)

This is the first of eight articles in the series Sizing & Selecting the Right Chemical Metering Pump.

Before we even start with sizing the pump, it is important to plan the application. We take into consideration various things such as the chemical, its physical and chemical properties, storage tank and its location, day use tank and its location relative to the pump and more especially its suction port, the injection quill and its distance from the pump, electrical power requirement etc.
Liquid to be pumped

The first thing we take into consideration is the properties of the liquid we are pumping.

Viscosity – If the liquid is viscous it would need to be pump with a slow velocity to allow for the flow of that liquid. If you pump too fast the liquid could cavitate or stall the flow.

Temperature – If the liquid is too hot or too cold it will affect the rest of the pump components. A very hot liquid could need a cooling jacket or materials that can withstand those temperatures. A liquid such as chocolate will solidify and clog the pump and may require a heating jacket to keep it flowing.

Specific Gravity – Heavier liquids will require flow capacity adjustments.

Off Gassing – Chemicals such as Bleach (sodium hypochlorite) could generate gas bubbles and cause air lock in the pump. These may require a de-gassing valve to be incorporated in the diaphragm head.

Concentration – Many times chemicals are diluted with water. A 10% concentration will have very different physical and chemical properties compared to a 50% concentration solution.

Particles – Particles in the liquid could clog the pump internals as well as the pipe. So design will have to keep in mind that the smallest areas in the pump will pass the […]

By |March 22nd, 2016|Metering Pumps Tips, News, Selecting the Right Pump|0 Comments

Sizing & Selecting the Right Chemical Metering Pump

In 2016 we will start a series of articles which address the very important issue of how to size, select, install and use a metering pump properly. As we all know, chemical metering pump applications are sometimes very complex and require planning and preparation from early on to ensure a successful installation. This series of articles are divided into the following eight sections:

1. Planning: Before we even start with sizing the pump, it is important to plan the application. We take into consideration various things such as the chemical, its physical and chemical properties, storage tank and its location, day use tank and its location relative to the pump and more especially its suction port, the injection quill and its distance from the pump, electrical power requirement etc.

2. Sizing: Here we start with the flow requirements and how much back pressure we encounter in the injection process. We also take into consideration the physical properties such as viscosity and density, and compensate for it. Dosage variation demands are also very important considerations.

3. Selecting the right pump: This is where you understand the different choices you have in types and brands of pumps and how to differentiate between them. We will also discuss life cycle cost versus purchase price of a pump.

4. Selecting the right material: Most chemicals are corrosive in nature and they require selection of material that is resistant to chemical attack. Knowing the exact chemical, its temperature and concentration is critical in selecting the right material.

5. Configuration: Do you want a leak detection system? Is the environment filled with flammable gasses or liquids in which case? What type of connections do you need for suction and discharge piping? These are the questions which will be addressed in this […]

By |March 18th, 2016|Metering Pumps Tips, News, Selecting the Right Pump|0 Comments