Frequently Asked Questions - Chemical Feed

If you’re pumping a gaseous chemical, such as sodium hypochlorite (bleach) or hydrogen peroxide, gas is probably forming inside the suction tubing or pump head. This causes the pump to lose prime and stop pumping. In most situations, you can manually re-prime the pump as a temporary fix. For a more permanent solution, you need a way to automatically remove the gas.

Peristaltic pumps (available from Stenner, Blue-White and others) are designed to push the bubbles through the pump head, preventing airlock. If you prefer diaphragm pumps, most of the solenoid driven diaphragm chemical feed pump manufacturers have also developed ways to eliminate this problem. For example, LMI and Pulsafeeder offer models with a degassing head.

Most manufacturers of mechanically driven diaphragm-type chemical feed pumps recommend installing a pulsation dampener on the discharge line to reduce excessive vibration and hammering.

A pulsation dampener is a pressurized vessel with an elastomeric bladder that acts like a shock absorber and delivers a constant, smooth flow. If you are frequently replacing cracked fittings on the discharge side of your pump, you may want to consider installing a pulsation dampener. Be sure to check for chemical compatibility when choosing a pulsation dampener.

USABlueBook offers several options. If you want to stick with chlorine, you can use a tablet feeder with chlorine tablets. A flow-through tablet feeder can easily be piped in place in your effluent channel and provide efficient disinfection at an affordable price. Tablet feeders are also available for use with dechlorination tablets.

If you want to use liquid sodium hypochlorite, USABlueBook offers a large selection of chemical feed pumps and chemical storage tanks. Our Technical Specialists are available to help you size a pump and chemical storage tank for your application.

Ultraviolet disinfection is another option. UV is very affordable and highly efficient. While there is an initial investment to set up these systems, they quickly pay for themselves by reducing the man-hours required for operation and maintenance. USABlueBook offers systems that have a lamp warranty of 10,000 hours. These lamps use about as much power as the lamp in your living room.

USABlueBook can help you with most of the available disinfection options. We recommend that you talk with your local regulatory agency when considering any of these options.

There are a number of reasons why a chemical feed pump will not pump. The first step is to consult the troubleshooting information in your pump’s manual, where you will find helpful hints on what to check for.

A diaphragm pump needs to perform two basic functions for proper operation:

1. It has to be able to pull the chemical into the diaphragm housing (suction).
2. It has to be able to push it out to the injection point (discharge).

Verify that the foot valve (if your pump has one) is clean and clear of any debris. The foot valve needs to remain in a vertical position in order for the internal check valve to function correctly.

Next, inspect the suction tubing and connections for leaks or cracks. A leak on the suction side of your pump may be hard to see and all fittings should only be hand tight. Never use a wrench to tighten a fitting. This may distort the seal, which will interfere with the function of the check valves and may even create a leak.

Check for leaks around the diaphragm housing. Most manufacturers incorporate a weep hole in the housing to detect a diaphragm failure. If your pump is leaking from this weep hole, remove the pump from service immediately, consult your owner’s manual and make the necessary repairs.

Verify the connections haven’t been over-tightened, and that the seals haven’t been distorted or smashed down too far. Next, look for crimped areas in the discharge tubing that could prevent the chemical from reaching the injection point.

Then, inspect the injection valve (if your pump came with one). Injection valves are generally installed on the underside of a horizontal pipe between the 6 and 9 o’clock positions, but space limitations and accessibility play a big role in the specific location. Check the injection valve for debris or other obstructions that could interfere with the function of the check ball and spring.

Last, verify that the pressure in the line into which you’re injecting does not exceed the maximum pressure capacity of your pump.

If none of these tips fix the problem, the problem could be with the drive end of your pump and may need further technical assistance. Contact USABlueBook’s Technical Specialists for assistance.

No. Using the same tablet feeder for both chlorination and dechlorination tablets can result in a dangerous chemical reaction. If your system requires both chlorination and dechlorination tablets, they must be housed in separate units. Typically, these units are separated, which allows for retention time for the chlorine to properly disinfect the effluent. When treated water contacts dechlorination tablets, the reaction is instant, so retention time is not as critical.

When pumping gaseous chemicals such as sodium hypochlorite (bleach) or hydrogen peroxide, using a flooded suction application will virtually eliminate the need for repriming. As the chemical off-gasses, the gas rises to the top of the tank and only liquid is fed to the pump via gravity.

Note: Pumps with degassing heads are NOT recommended for flooded suction applications, because the chemical would continuously exit the bleed port.

Note: Please wear proper protective equipment when handling hazardous chemicals.

• Wash the pump, tubing and fittings out with clean water. To do this, place the suction tubing and discharge tubing (including injection fitting) in a container of clean water.
• Let the pump run in the clean water for a couple of minutes to remove and neutralize all traces of the chemical you are pumping.
• Remove the mineral deposits. To do this, place the suction tubing and discharge tubing in a container full of undiluted vinegar or PlantPRO Chemical Feed Pump Cleaning Solution (stock # 351154).
• Let the pump run in the solution for 5 to 10 minutes (longer if needed); then let it soak for 1 to 2 hours.
• Flush out your pump, tubing and fittings to remove any excess vinegar (or cleaning solution). To do this, repeat steps 1 and 2.

This varies by model. For a specific list of what is included, view the individual product page for each pump or review our catalog. In general, most pumps include tubing, ceramic weight, injection valve and a foot valve. Pumps with pulse and 4-20 mA capabilities usually include a connector for input control, but some are sold separately. Pumps supplied with NPT fittings do not include tubing, weight or either valve.

In most cases, maximum suction lift is 5 feet for a diaphragm pump and 25 feet for a peristaltic pump. High viscosity diaphragm pumps have a maximum lift of 3.5 feet; however, flooded suction is recommended for viscous chemicals or chemicals that off-gas readily.

The following is a basic list of information you will need to consider when you are looking to purchase a chemical feed pump:

• Chemical compatibility: What chemical are you pumping?
• Output requirements; How many gallons of chemical will you be pumping per day?
• Discharge pressure: How much pressure is in the line you will be injecting into?
• Control options: How will the pump be controlled? Manually? Pulse or 4-20 mA signal?
• Voltage required: Do you need 120 VAC or 220 VAC?

For assistance with choosing the best pump for your application, contact USABlueBook’s Technical Specialists.

Diaphragm pumps use a flexible diaphragm to displace the fluid. They are often preferred for applications requiring precise dosing of chemicals due to their ability to handle a wide range of fluids and maintain accurate flow rates against higher injection site pressures.

Peristaltic pumps use rotating rollers to compress a flexible tube, creating a positive displacement action. These pumps are known for their gentle pumping action and are suitable for applications where off-gassing chemicals cause airlock and have lower injection site pressures.

When selecting a pump for a specific application, factors such as flow rate, head, fluid viscosity, chemical compatibility, and system requirements should be considered to ensure optimal performance and efficiency.

For assistance with choosing the best pump for your application, contact USABlueBook’s Technical Specialists.