Gas feed systems are used to deliver three types of gases in swimming pool care. The three different gases each have a specific job when they are used. Firstly, there is chlorine gas which is used as a pool disinfectant. Next there is carbon dioxide gas. This particular gas treatment is fed into swimming pools as a pH lowering agent.
Carbon dioxide is usually used along with sodium hypochlorite which is also a pool sanitizer (disinfectant).
Both of these gases are used in their liquefied state and are contained in cylinders that are filled under pressure.
Another gas that is commonly used in swimming pool care is ozone.
Ozone is a powerful oxidizing agent and it is far better than dioxygen. It is unstable at high concentrations and it is very toxic to humans. Because ozone is so unstable at high concentrations, it has to be generated on site. It is first an oxidizer and then a disinfectant.
Feeding the chlorine gas from its pressurized gas cylinders usually calls for the installation of an automatic gas feed system. This this gas feed system (device) is usually attached by some type of yoke mechanism. The gas is controlled by an adjustable device that meters in the desired amount of chlorine gas properly.
Once you have the correctly installed a chlorine gas feed system, you can feed the correct amount of chlorine gas directly into your swimming pool. This is done through your swimming pool circulation or return line.
Most chlorine gas feed systems rely heavily on the venturi principle (vacuum pressure) for delivery. The venturi principle allows the gas to be drawn in and properly mixed into the flow of your swimming pool water circulation. This process or delivery system, will ensure that the chlorine gas is properly dissolved as well.
The desired pool chemical reaction you want to achieve are as follows:
All the above chemical reactions will only be achieved after the dissolution of the chlorine gas has taken place. There are some gas feed systems that rely on booster pumps that has a side stream injection.
As I mentioned earlier, there are three different types of gases that are used in recreational water treatment. Using these gases in your swimming pool care requires the use of a special type of gas feeder. These particular feeder devices are listed below.
Chlorine Gas Feeder - When installing chlorine gas feed systems, you should make sure that the location is suited for the installation. The gas feed system has to be installed in a room that is well ventilated also. This is usually called the equipment room and it must have a forced air ventilation system that is more than capable of giving you a complete air exchange.
This air exchange must be in one minute or less. Why? The truth of the matter is that chlorine is a gas that is much heavier than air which means it can be hazardous to your health. It is green in color and is known to collect in low areas. The odor from this gas treatment is very distinctive and can easily be detected in concentrations as low as 0.2 to 0.4 ppm (parts per million).
Whenever an individual has an acute or short term exposure to levels of chlorine gas greater than 30 ppm, it results in some serious health issues. These health problems consist of the following:
However when exposure is of a much lower level (less than 3 ppm), the chlorine gas becomes a very potent irritant. The lower levels of exposure will cause health problems like these:
Your chlorine gas feed systems should be checked regularly for leaks on a daily basis. Studies have reported the following results.
The health problems listed above are why all chlorine gas feed systems should be installed in an area that is above ground level. Chlorine gas is an excellent pool sanitizer that is very effective in swimming pool care; however, very few pools still use this product as a first choice in pool sanitation.
This is simply due to the regulatory restrictions that are induced by the hazard of a potential leak. Chlorine gas feed systems are more commonly used on larger swimming pools. The most severe hazard that can occur with the use of chlorine gas in water treatment, is when you get a rupture with one of the pressurized cylinders.
Most chlorine gas cylinders are portable and are usually filled off site by the supplier. The weight of the cylinders ranges from 100lbs (45kg) to 150lbs (68kg). Whenever you are using these pressurized cylinders for your swimming pool and spa water treatment, the chlorine must always be feed into the water as a gas.
All portable cylinders must be stored in their upright position which will prevent accidental damage to them. Any damage to the cylinders could be very dangerous to you or service staff personnel. This safety measure applies to both the filled and empty cylinders.
Another safety measure that will help eliminate any potential hazard is to have the cylinders chained or strapped to the wall or some other fixed device.
The valves and outlets for the cylinders should also be protected from any potential damage as well. Your chlorine gas supplier usually supply protective caps for this purpose whenever the vessels are not in use. You can use the first in first out principle here. This lets you know when a particular cylinder or cylinders came in and when they were placed into operation.
The importance of proper pH level control in your swimming pool and spas cannot be over emphasized enough. Your pH level affects every aspect of your pool water chemistry. The fact of the matter, is that if the pH level of your pool or spa is too low, then your pool water will become very corrosive.
This will cause serious problems in your swimming pool or spa. On the other hand, if your pH level is too high, then you run the risk of having scale formation in your pool.
Again this will cause serious problems with your pool which can be very costly. For the past 10 years, many pool and spa operators have used and are using carbon dioxide gas as an alternative means of controlling the pH levels in their swimming pools. Usually, swimming pool and spa operators use muriatic acid as their means of lowering their pH levels.
This form of pH level control is often used when the primary choice in pool disinfectant is either Sodium Hypochlorite or Calcium Hypochlorite. Carbon dioxide is a chemical that is used for swimming pool care and when its dissolved in water, it produces a weak acid called carbonic acid.
Whenever the carbon dioxide gas is inserted into your pool's return line (circulation), the resulting chemical reaction (carbonic acid) will reduce the pH level in your swimming pool or spa water. If you are using carbon dioxide as part of your pool care treatment, you have to control the release of the gas properly and safely.
A release regulator must be installed with the gas feed systems for this pool chemical treatment. Failure to do so could cause your carbon dioxide gas to be release to quickly which could cause your injection system to freeze up. The feed system of a carbon dioxide gas treatment set-up also uses an automatic feeder control system.
The automatic control system is an excellent way of controlling the release regulator in your CO2 gas feed systems.
The injection of CO2 is accomplished by one of two ways.
You can use either a booster pump or a venturi (vacuum) system as your means of delivery for the CO2 gas into your pool's circulation line.
You must remember...injection of this pool chemical treatment should occur downstream from your circulation components.
This includes your pool sanitizer injection system as well.
As with all types of swimming pool chemicals, there are advantages and disadvantages. Lets look at a few disadvantages of using CO2 gas.
Any pool or spa operator who uses chlorine or carbon dioxide gas as part of their swimming pool care, should consult with their local health department on proper training requirements for these type of products. Proper training with these chemical products will help you to safely maintain your carbon dioxide and chlorine gas feed systems.