Achieve Accurate, Dependable Dosing of Sodium Hypochlorite

Chlorine has been used to disinfect water in the U.S. since the early 1900s, and it remains the most frequently used water and wastewater disinfectant worldwide due to its low cost and effectiveness at deactivating a wide range of pathogens.

The two most common chlorine products for these applications are chlorine gas (Cl2) and sodium hypochlorite (NaOCl), a.k.a. bleach. For the most part, both chlorine compositions function the same way, in that they dissolve in water to form free chlorine in the form of hypochlorous acid (HOCl) and hypochlorite ion (OCl−). Treatment plants target the same parts per million of free chlorine regardless of which chlorine source is used.

Despite this, they are two very different products. In this article we will discuss liquid chlorine, Sodium Hypochlorite.

Safety Considerations

Sodium hypochlorite is considered to be a safer alternative than chlorine gas, but the chemical should still be treated with respect, and although safety protocols may not be mandated, it is recommended that they be in place.

Operator Comfort

Closely related to safety is the issue of operator comfort. Although more potent than household bleach, sodium hypochlorite is still a familiar chemical to most operators.

It’s important to note that sodium hypochlorite should never be stored near other chemicals, particularly acids. If there is a sodium hypochlorite spill or leak proper PPE should be worn until the danger is mitigated.

Another source of comfort when using sodium hypochlorite is familiarity with the equipment used to deliver the chemical. A good chemical metering pump will accurately and dependably dose the proper amount of sodium hypochlorite into the system.

Chemical Metering / Dosing Pumps

The two most common types of chemical metering pumps used for dispensing liquid chlorine are peristaltic and diaphragm models.

Peristaltic pumps are extremely effective when pumping fluids that contain trapped gases because they are not affected by air bubbles. The bubbles simply move through the pump tubing as the pump maintains a constant rate of flow. There is no potential for vapor lock, and peristaltic pumps do not lose prime. Due to this characteristic, Peristaltic pumps have been widely accepted as the preferred technology in many water and wastewater treatment applications.

In contrast, the intermittent pumping action of diaphragm pumps, specifically during the suction phase of the cycle, can cause gas build-up. This buildup of gases can lead to vapor lock, and the pump may lose prime.

There is a third option to consider, a multi-diaphragm pump is a more recent design that can solve several issues traditional single diaphragm pumps experience. It utilizes two diaphragms connected through a central shaft. This shaft pulls one membrane to create suction while simultaneously pushing the other membrane to discharge liquid. The push pull combination creates a smooth, near continuous flow that allows the pump to run at high speeds with virtually no chance of vapor lock or lost prime.

FLEXFLO® M3 Peristaltic Chemical Metering Pumps dependably deliver smooth and accurate chemical dosing to the system. Operators appreciate the pump’s bright, easy-to-access, and highly responsive 5-inch display screen which features easily recognizable icons, is highly intuitive, and as simple to operate as a smart phone.

FLEXFLO® M3 pumps have a broad 10,000:1 turndown ratio to meet a vast range of dosing requirements, and they’re equipped with a brushless DC motor for trouble-free and energy-efficient service.

M3 remote control signal options include Pulse, 4-20mA, Modbus TCP, EtherNet IP, and PROFIBUS for enhanced supervision and automation for critical metering and transfer applications.

If a diaphragm pump is preferred, which would be the case in higher pressure applications, the CHEM-FEED® MD3 should be considered. MD3 is equipped with Blue-White’s Exclusive Dual Diaphragm Hyper Drive Technology for Smooth, Near Continuous Feed – like a Peristaltic Pump but with no tube to change, and this technology virtually eliminates the possibility of vapor lock, water hammer or loss of prime.

Each MD3 is outfitted with the incredible DiaFlex® Diaphragms. These exclusive diaphragms are engineered to last the life of the pump, making MD3 very low maintenance.

There’s a large 5″ display for easy viewing and simple operation of the intuitive touchscreen controls, plus advanced communication protocols that include 4-20mA, Pulse inputs, Industrial Protocols, and Remote Start/Stop.

Pump Maintenance should also be considered. Other than occasional pump tube replacement, peristaltic units do not require regular maintenance. Diaphragm pumps, on the other hand, require ongoing maintenance as valves and pump heads must be regularly cleaned.

In conclusion, whether you choose Peristaltic or Diaphragm Technology, both FLEXFLO® M3 and CHEM-FEED® MD3 are built for long-term service with new software capabilities that will roll out in future firmware updates and will be field upgradable.

Written by:
Blue-White® Industries
714-893-8529

Download (PDF)