Erosion Feeders Are Dry Chemical Feed Systems

Chlorine erosion feeders, or flow through chemical feed systems, are feeders that operate on a stream of water which contacts the dry chemical located inside. The stream of water causes the dry chemical to erode and dissolve into the flowing water.

Proper operation of a dry chemical feeder depends on a few concepts! These concepts include:

  • The pressure and/or suction that is created by your swimming pool filtration or circulation pump.
  • The differential pressure that occurs between the suction and pressure side of your swimming pool pump.

There are some erosion dry chemical feeders, which use a mechanical gate or rotating screw to move the chlorine granules into the path of the flowing water.

It is during this process, that the chlorine granules are dissolved into the water which is then fed into your swimming pool.

Dry pool chemicals not only come in granular form. They can also be purchased in tablet form which come in assorted sizes and shapes. Dry erosion feeders that use the larger size chlorine tablets (3 inch), have a plate installed inside that prevents the tablets from being completely submerged in water.

This separation plate has holes that allows the stream of water to hit the bottom of the tablets; thus, causing them to slowly erode and dissolve into the water. You can find this concept or type of erosion design in a PPG Power Base chlorination system. An example of one is pictured below.

Chlorine Erosion Feeders

Using Venturi Injectors To Operate Erosion Feeders

Sometimes a dry chemical erosion feed system is installed and operated on the pressure side of your swimming pool circulation pump. If this is the case, operation of the chemical feeder will depend on a venturi effect (vacuum) to operate.

A venturi system is one that creates a vacuum pressure as water (fluid) passes through it. The output or discharge side of your dry chemical feed system is connected to the suction port of the venturi system. During this process, the chemical solution will be sucked into the flow of circulation for your swimming pool or spa.

How Effective Are Chemical Erosion Feeders

At this point, the erosion of a chlorine tablet is gradually wearing away in the pool chemical feeder. If you decide on using this type of pool sanitizing system, the effectiveness of your system will depend on these four basic factors...

  • The solubility of the pool chemical product that you are using.
  • The flow rate of the water passing through your erosion feed system.
  • The total surface area of the chemical tablets or pellets that are being exposed to the water stream.
  • The temperature of the water flowing through your erosion feeder. This is the supply water from your swimming pool or spa.

Maximizing The Effectiveness Of Erosion Feeders

Observing or reading the instructions and operators manuals that manufacturers supplied with the purchase of erosion feeders, your feeder, will help you maximize its full potential. These manuals will show you how to professionally install the chlorine feeder and properly control it as well.

From your operator's manual you will be able to determine the pool or spa size...that your new pool chemical feeder/s can treat effectively.

As a swimming pool operator or homeowner of a pool or spa, it is vitally important that you understand the safety information that is provided for you by the manufacturer on your erosion feeder.

This, my friend will eliminate any potential health risks to you or someone else. If you have erosion feeders that are improperly operated, there is an enormous potential that they could; God forbid, rupture, or explode.

This is an extremely dangerous situation which could occur when you or some other attendant is around. This could send the lids as well as pieces of pipe flying which can cause serious injuries or death.

During the operation of your erosion feeder, the flow of water must be carefully adjusted. This is how you will maintain the proper amount of disinfectant going to your swimming pool or spa water system.

There are some commercial erosion feed systems that are installed with one or more flow regulating valves. Some State code regulations may require you to have a flow meter install as well.

Chemicals That Are Used In Erosion Feeders.

As I mentioned earlier, dry chemicals not only come in granular form. They can be brought in solid tablet form as well. These chemical tablets can either be solid chlorine releasing or bromine releasing.

Emphasis is put on these types of tablets because they are the most used ones in an erosion feeder system. Hence the names chlorinator type feeders and Bromine type feeders.

Types Of Erosion Feeders Used In Swimming Pool Treatment

There are several types of dry chemical feeders that are available for spa and swimming pool sanitation. Examples of some of these devices are as follows:

  • Pressure Erosion Dry Chemical Feeders - These types of feeders are usually installed downstream...away from your swimming pool filters and swimming pool heaters. They are plumbed directly into your filtration or circulation line which, is under full line pressure.

If your swimming pool pumps and filters are installed below your water surface level, it is important that you have isolation valves installed on each side of your erosion feeder. These valves are closed before opening the unit. They also allow you to carry out any maintenance on the system as well.

All erosion chemical feeders that are designed to operate under pressure, must have a bleed off valve.

These bleed off valves are also referred to as pressure relief valves. They allow you to safely release the pressure inside the unit before it is open. A word of caution: Never open a pressurize dry chemical feeder until you have safely released the pressure within the unit. Your circulation system has enough internal pressure to blow the lid/s completely of your feeder.

This is an extremely dangerous situation because the lid can be launched through the air at a speed that can damage or destroy your equipment. Regrettably, there is also the potential danger of injury or death to the pool operator.

  • Pressure Differential Erosion Feeders - Installation of these types of chemical feeders are usually downstream from your swimming pool pumps. Pressurized water from your pool pumps is fed through your mechanical feeder during normal operation. The return line or discharge side of the feeder is connected to your circulation line. 

This connection is at a point that is farther downstream which is at a much lower line pressure. The difference in pressure is what forces the water to flow through your erosion feeders. The differential pressure here is created by one of the following methods: A booster pump that forces the chemically treated water from your chemical feeders to a pressurized line in your circulation system.

Through a vacuum pressure that is created by a venturi injector system. The vacuum that is created using the venturi injector, draws the chemical treating agent from your chlorine feeder directly into your pool circulation line. This is safely done through a throttling valve loop system.

There is a valve restriction on one side of the loop. When you are installing an erosion dry chemical feeder, your supply water should always be properly filtered. There are some installations that are supplied with water directly from the discharge side of the swimming pool pump.

With this type of installation, the outlet to the feeder unit is connected to the return line in your circulation system. This of cause, is after your swimming pool heating system. Installation of this type uses pressure drop across your swimming pool filters and pool heater. This is how the positive flow through your feeders is developed and maintained.

  • Spray Erosion Dry Chemical Feeders - These are feeders that are occasionally used with a Calcium Hypochlorite system. The Calcium Hypochlorite tablets in these type of feed systems is sprayed with incoming water instead of them being immersed in the water. 

With this type of dry chemical feeder, a venturi injector system or booster pump is often used as well. To avoid the buildup of calcium scale in the system, it is vitally important that you carry out a regular preventive maintenance on the feeder.

Failure to do so will result in your feedlines becoming clogged. As a result of your feed lines being blocked, your erosion feeder eventually will fail.

Although these feed systems are designed to prevent scale formation, scaling can still occur and become a big problem.

The fact of the matter is, Calcium Hypochlorite has an extremely high pH range and an exceedingly high Calcium content.

If by chance you decide to use this type of feed system, it is particularly important that the discharge lines from your chlorine erosion feeder have large enough diameters and see that you clean the lines out regularly.

  • Pressure To Vacuum Feeders - This type of dry chemical feed system is inexpensive. The fact of the matter -is that a booster pump or a venturi injector system are not required for this type of installation. The water flow through this chemical feed system is controlled with a valve. The flow is driven by a pressure differential on your swimming pool system. This pressure differential is achieved when water flows from a portion of your pool circulation system. This water flow is under pressure which is tapped and redirected. The water flow is redirected through a flow meter and then through your dry chemical erosion feeder. After the water entering the feed system is chemically mixed, it exits your feeder and is returned to your swimming pool. With this type of set up, the water usually returns to the pool upstream from your swimming pool pumps which are under vacuum pressure.

Problems Associated With Pressure To Vacuum Erosion Feeders

Installing this type of chemical feed system will cause certain drawbacks. For instance, most of the pool chemicals being fed to your swimming pool may cause deterioration. This deterioration is usually seen in your POOL circulation equipment such as...

  • Pump impellers (brass).
  • Pump housings.
  • Pool heaters.

If you utilize probes to measure the chemical levels in your swimming pool, you must ensure that they are not giving you a false reading. You want to be concern about this because water that has just being chemically mixed...can give a false reading when it passes the head of your probes.

Specialized Mechanical Erosion Feeders

In some chemical feeder systems, pool chemicals are metered into what is called a chemical feed tank. The metering process is accomplished by a screw mechanism which is either a mechanical gate or shutter type device.

Again, the output or discharge of this type of system is drawn into your pool circulation line by a venturi injection (vacuum) system or by a booster pump. When using mechanical dry erosion feeders, the tank must be properly sized.

This will allow your pool chemicals the time needed to properly dissolve or erode. The correct size erosion feeder will also allow better delivery of the chemicals to your swimming pool or spa. There are many distinct types of designs for a dry chemical feeder system; therefore, you always want to install the one that is right for water you are treating. 

Fact: You want a feed system that you can afford and at the same time, one that will properly maintain your pool water chemistry.

The safety of your pool bathers is your responsibility; therefore, you must make sure that your swimming pool water is properly sanitized at all times. So, protect your swimmers...try using dry chemical erosion feeders.

Erosion feeders helps you eliminate swimming pool contaminants!

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