1) Flexible Connector Line

This line is used to connect the isolating valve of container cylinder to the header valve in the manifold header pipe and is made of Cadmium plated copper flexible tubing (1/4" OD x 6' or 10' length). The isolating valve assembly will trap the gas in the flexible connector when replacing the gas containers/cylinders, and prevent moisture from entering the line. Moisture inside of flexible connector combined with gas will cause corrosion. Keep isolating valves closed when changing the gas containers/cylinders. When replacing flexible connectors, the header valves if possible should be closed to prevent gas from escaping and moisture from entering the manifold. Header valve permits isolating the flexible connector from the manifold piping for maintenance or replacement.

2) Pressure Manifold Line

The pressure manifold allows for the coupling of any number of chlorine containers/cylinders to a common header as required for a gas feed system. The valves on horizontal manifolds may be piped in either direction. The maximum size of a chlorine header system under pressure in any applications should never be larger than one (1) inch. The pipes size & materials are as ff.:

• 3/4" seamless carbon steel, grade B, Sch. 80, types S, ASTM A-106 pipe for Gas Withdrawal
• 1" seamless carbon steel, grade B, ASTM A-106 pipe for Liquid Withdrawal

Note that prior to assembly, the threads of header valves should be coated with a mixture of litharge and glycerin for a permanent joint or Teflon tape for a serviceable connection to above manifold pipe.

The entire length of the chlorine gas pressure manifold should be heat traced with strip heaters to prevent reliquefaction of chlorine gas in the manifold. Drip legs with pad heaters should also be supplied. The number and orientation of the drip legs should be in accordance with Engineering Data Sheets A2.62107 and A2.62108.

In preparation for use, all chlorine pressure piping should be pressure tested. Hydrostatic testing of piping requires extensive drying before chlorine introduction. This can be done by passing steam through the lines, from the high end, until the lines are thoroughly heated. Disconnect the steam source and thoroughly drain all low spots and pockets. With the lines still warm, blow dry air, dew point -40^oC through the lines until they are dry. This may require several hours. After drying, pressure test with dry air or nitrogen to 150 psig.

3) Vacuum Line

With remote mounted ejectors, the optimum size of the vacuum line is of prime concern since the gas feeder operation is entirely dependent upon the vacuum created by the ejector. The maximum and minimum vacuum levels created by the ejector should be:

• Maximum Level: 22 - 23" Hg
• Minimum Level: 8 - 10" Hg

A minimum of 10" Hg allows purging of entrained air or gas that may accumulate in the solution lines. The vacuum line connecting the gas feeder components is normally designed for a total friction loss of 1.5 - 1.75" Hg at 68^oF with a 22 - 23" Hg vacuum level at the ejector.

The design procedure steps for determining vacuum lines are some complex since the optimum pipe size for vacuum lines between the chlorinator and the ejector is subject to a great deal of scrutiny, but we use the maker's suggested sizing table. In general, the vacuum line is recommended to use a flexible tube of high density polyethylene for up to 5/8" and Sch. 80 PVC Pipe for larger than 5/8".

4) Solution Line

The piping downstream from the ejector is the chlorine solution line. It is permissible to manifold the ejector discharge from two or more chlorinators into one point of application (Provided the solution line discharges into a multiple diffuser system so that there is one diffuser per ejector.), but a solution line to the point of disinfection should not be manifolded to any other point of application. The most desirable arrangement is for each ejector to have its own solution line and diffuser. The bubbles of gas, which release a tremendous amount of carbon dioxide and other gases when some water is carrying a chlorine solution, in the solution passing through the rotometer can cause sufficient vibration to severely limit the accuracy of the reading. Glass tube rotometers should not be used because this vibration can cause the rotometer float to shatter the glass tube. The only rotometers satisfactory for chlorine solution lines are the straight through metal (Hastelloy C) or PVC tube type with dial indication.

The amount of water required must be sufficient to limit the chlorine solution strength to 3,500 ppm. The excess concentrated solution (molecular chlorine breaking out of solution) can cause fuming at the point of application if open to the atmosphere, and gas binding in solution lines under low negative heads. A broad rule of thumb is 40 gal of water/day/pound of chlorine.

Solution line lengths should be kept to an absolute minimum. The correct diameter of a solution line is determined by:

• Rate of solution flow of (ejector outlet)
• Allowable friction loss. Generally the friction loss must be kept low so the back pressure at the outlet of the ejector is not increased.

From the point forward of ejector, a corrosive chlorine solution will be encountered which requires special materials. The chlorine solution lines can be either three types of pipes, which are commonly used for solution service under normal temperature conditions (below 100^oF). These are:

• Sch. 80 PVC pipe, Grade A, Type 1 for smaller than 6" size.
• Sch. 40 rubber lined black steel pipe for larger than 6" size or where is required a rigid pipe.
• Rubber Hose for strong chemical solution: Suitable troughs are required for support and protection. Where hose is likely to be subjected to any appreciable negative head, it should be internally reinforced to prevent collapsing. Hose is available in two general types:

* Wrapped hose is available in lengths up to 50 feet and all common sizes through 2" inside diameter. Larger sizes are available on special order. This type of hose can be reinforced externally against pressure or internally to prevent collapse.

* Molded hose is available in longer continuous lengths and all common sizes up to and including 1-1/2" inside diameter.

Valves on the solution lines can be either diaphragm or ball type. Diaphragm types are usually flanged, rubber lined, or PVC-lined cast iron Saunders-type valves. The ball type PVC valve is preferable up to 2-1/2" size, although the ball type valve is available in much larger sizes. The diaphragm type should be considered for sizes 3" and larger.

5) Diffuser Pipe Line

There are so many types of diffusers, but the perforated diffuser and pipeline diffuser are usually applied to the mixing of chlorine solution and cooling water in basin.

• Perforated Diffusers: The pipe is perforated, so that chlorine solution is discharged mostly below the minimum water surface level. This diffuser eliminates the problem of the accumulation of debris which is always prone to collect on any object projecting into the flowing cooling water. The diffuser should be designed to be easily removed with the flanged connection. This may be necessary to clean the slot of slit and other debris as well as to inspect for plugging of perforations.
  
  Experience indicates that over a period of three or four years chlorine solution diffusers do plug up in cooling tower application. The deposits that cause the trouble appear to be the result of highly chlorinated organic compounds containing a large portion of grease, which provides a waxi like binder.
  
• Pipeline Diffusers: This is well known that the best mixing occurs when the chlorine solution is discharged into the center of the pipe, this is not practical because of the debris that will accumulate on the projected diffuser. Therefore the diffuser must end flush with the inside wall of the conduit, but it should be designed for a velocity of 22 - 26 feet/sec in order to project the chlorine solution toward the center of the pipe. This velocity across the diffuser orifice will result in an 8 - 10 feet pressure drop. Therefore the chlorine solution line and ejector water supply will have to be designed to accommodate this additional ejector back- pressure.
  
  It is reasonable to locate the diffuser pipe line front the screens of the sump fits of cooling water circulation pump for the best mixing in the cooling tower basin. Static pressure at the discharge of ejector should be limited to no more than 4 - 5 psi, for the following reasons: (1) Ejector operating pressures and water quantity escalate rapidly as the back pressure on the ejector rises beyond 5 psi. particularly when the chlorine feed rate is in excess of 500 lb/day (For chlorinator 500 lb/day and smaller this back pressure limitation is not a factor.). (2) Head loss through the diffuser is used as a chlorine mixing devices. Allow 8 - 10 feet loss through the diffuser for this function. To meet this requirement ejector must be located as close to the diffuser as possible.

The diffuser has a negative head in most cases of the cooling tower application. If it is not properly designed and anytime a negative head exists in the chlorine solution line, molecular chlorine will break out of the chlorine solution and cause serious gas emission at the diffuser.

Therefore, if the cooling water level at diffuser is below ejector throat, the hydraulic gradient from the ejector to the diffuser must be calculated to provide a reasonable ejector back-pressure. Assume this back-pressure is 5 ft (approx. 2 psi). Then the friction loss through the diffuser holes + (plus) the line losses - (minus) the difference in elevation between water level and ejector throat must equal approximately 5 ft of head of previously mentioned back pressure. This is one of the reasons for having a compound gage on the solution line at the discharge of ejector.

The diffusers are customarily made up of Sch. 80 PVC pipe and fittings. If the specifications for underwater piping require steel construction for additional strength, all the diffuser piping must be made of rubber-lined and rubber-covered steel pipe. The diffuser holes must also be rubber-covered. Nuts and bolts for assembly of the underwater portion should be 316 stainless steel. The diameter of diffuser pipe must be no less than the ejector outlet size and in some cases may be larger, since a negative head will be to create a siphoning action. The optimum size of perforated holes (orifices) and the number of holes per feet must be carefully considered.