ISO 9001 :2008 quality  company RSS feed	Aeration & Oxygenation systems Environmental & sustainable water treatment to save the planet	| home page | Contact us  | About us |  Search |  Shop ||
| Homepage aeration | Aeration systems | Effluent & Landfill leachate | Lake aeration and treatment  | Lake aeration & destratification | Aquaculture

The Dryden flat plate ceramic diffuser is a high performance micro-bubble diffuser designed for use with the following gases

Oxygen

Ozone

Carbon dioxide

Nitrogen

Air

If other gases are to be used with the ceramic diffusers, please advise Dryden Aqua for clearance. If the diffuser is to be used with air, the air supply must be 100% oil free and filtered down to 0.1 microns using a cartridge filter and a carbon filter in order to remove any solids that may block the diffuser internally.  If your gas supply is not clean, then it is important to fit filters, this can sometimes be a problem with compressed cylinder industrial gas supplies

The Dryden Aqua diffusers is a high performance flat plate ceramic diffuser. The diffuser frame is manufactured from cast aluminium and then enamelled in Dryden Aqua green. The ceramic plate is secured in place using a high performance industrial epoxy. Ceramic is a very strong material, however if mis-treated there is a risk that the plate can crack. The design of the Dryden diffuser is such that the plate is fully supported internally to improve the structural strength and impact resistance. If a diffuser breaks from gas hammer shock loads, then usually the plate will just crack and all parts of the ceramic will be held in place.  This is a unique safety feature of the Dryden Aqua Product.  All diffusers are pressure tested to 20 bar.

The key performance feature of the Dryden ceramic diffuser is the mist of fine bubbles produced from the plate. When used according to the instructions, the plate will produce bubbles of a size between 10 microns and 200 microns to give a diffusion cloud like milk.

•  The diffuser when used in a tank should be located in the following position

• The diffuser should be sitting horizontally to avoid bubble coalescence
• Install diffuser in the deepest point in the tank, this will give the longest residence time of the bubble cloud in the water
• There should be no obstructions in the path of the bubble cloud; obstructions will cause the bubbles to coalesce.
• A horizontal flow of water across the diffuser will improve performance
• Do not place two diffusers side by side
• Minimum operating depth is 500mm, never turn the gas supply on with the diffuser out of the water.

Health & Safety

Oxygen can be a very dangerous gas with a risk of fire or explosion. All health and safety issues relating to the use of oxygen (and other gases) should strictly adhered to at all times.

Explosion and fire hazard

Specific attention should be paid to insure that all fittings in contact with oxygen are de-greased and are always free from oil, fats or other potentially combustible hydrocarbons. All fittings used with the Dryden ceramic diffusers should be compatible with the gas employed. In some cases not all of the oxygen will be dissolved into the water, under these conditions there may be an increase in the oxygen levels on the surface of the water, in the gas space above the tank, or in the room where the equipment is located. This point should be noted and the appropriate health and safety features implemented appropriate to the gas employed.

Pressure and ceramic hazzard

The maximum operating pressure of the diffuser is 45psi, the gas lines supplying the diffuser must be fitted with pressure relief valves or automatic shut down facilities that prevent any differential pressure in excess of 50psi across the diffuser. Do not operate the diffuser, or pressurise the diffuser when out of water. The diffuser must always be at least 500mm below the surface of the water when the gas is applied. Do not touch or remove the diffuser when in use, do not put your had or any part of your body closer than 500mm to the diffuser when in operation. The use of the Dryden diffuser, and all aspects relating to health and safety are the responsibility of the users. Dryden Aqua accepts no liability or consequential loss as a result of the use of the diffuser.

Safety feature

Dryden Aqua ceramic diffusers are the strongest and safest diffuser available, the diffusers are batch pressure tested to 20 bar. The static pressure test is therefore up to 10 times the working pressure. For health and safety you normally only need to pressure test to 1.5 times the working pressure.  The diffuser plate is fully support in a very strong cast aluminium frame and epoxy bonded to the frame. If the diffuser is over pressurised or  subjected to a transient high pressure spike, then normally the diffuser will just crack to release the pressure without the ceramic shattering into small missiles.  This is a unique feature of the Dryden Aqua diffuser.

Specification

Maintenance

 The Dryden Aqua micro pore ceramic diffusers have been designed to give a long and trouble free life. When the diffuser is used in water it will be prone to both chemical and biological fouling. The diffuser should therefore be cleaned at periodic intervals. If the diffuser appears to be fouled, or if the gas flow rate starts to fall off, then it is and indication that cleaning may be required.

Cleaning procedure

1. Remove diffuser from water

2. Clean with a bristle brush to remove gross debris

3. Wash in clean fresh water, or water containing a mild detergent

4. Allow to dry

5. Rub with emery paper 240 grade

6. Rinse in fresh clean water

7. Dry diffuser and place in store, or place back into use

Diffuser Blockage

The pressure differential across the diffusers should be approx 2 bar during normal use, however occasionally the diffusers can become blocked for the following reasons;

1. Ferric and carbonate salts form on the surface of the plate, they are usually removed by the 240 grade abrasive paper, however if it is not affect then a dilute acid such as acetic acid or citric acid may be used to dissolve the carbonates and metal salts.

2. If the diffusers are not cleaned after use, a biofilm can gradually develop inside the diffuser, in order to remove the biofilm soak the diffusers in a 1 % solution of sodium hypochlorite  at a pH between 6.5 and 7.5 for a period of 12 hours. If chlorine dioxide is available, this is much better as removing biofilm.  Never mix hypochlorite with an acid, this will release toxic chlorine fumes...extremely dangerous....

3. The hypochlorite is usually effective at removing biofilm contamination, but if the diffusers have been allowed to become grossly contaminated then a 2% solution  of sodium hydroxide at 50 deg C for 1 hour works well. However caution should be exercised when dealing with sodium hydroxide because it is very caustic. Comply with all health and safety regulations.

4. If not of the above work, the diffusers may have been exposed to a dirty gas, compressed gas cylinders do not always provide a clean gas unless you use hospital grade. Liquid oxygen should be clean, and oxygen provide by PSA systems is usually very good. The problem is mainly with gas cylinders.  The above procedure should be able to clean the inside of the diffuser, but if there is gross contamination of the plate it may require an extended soak period in a dilute acid such as acetic or citric acid. Only every use organic acids with the diffuser. The brass fitting may experience erosion from the acid, so only use a weak acid and do not soak for any longer than is absolutely necessary.

Disinfecting

 The diffuser may be disinfected using a maximum of 50mg/l of hypochlorite solution. Fill the diffuser with the hypochlorite solution and allow to sit submerged for 10 minutes. Remove the diffuser, drain out the hypochlorite solution and then wash in clean freshwater to remove all traces of the disinfectant.

Storage

Storage temperatures should be between +5 degrees centigrade and 60 degrees centigrade. Do not expose the diffusers to temperatures above 60 degrees centigrade.

Dryden Aqua provides a guarantee against any defect in the goods that is attributable to the manufacture of the product for a period of one year from the date of purchase or 16 months from the date of manufacture, (which ever is the shorter time period). Defective goods should be returned to Dryden Aqua suitably packaged for inspection. If it is determined that the fault was due to defective parts or manufacture, the goods will be repaired or replaced free of charge within the UK. For goods returned from out-with the UK there will be a returned goods charge at cost price.Dryden Aqua guarantee is conditional upon the following;

• The equipment must have been used and maintained according to Dryden Aqua instructions
• The guarantee will not cover any defects resulting from misuse of the product, neglect, accidental damage, over pressurising or operation of the diffuser out-with the design specifications
• Any attempt of the purchaser to repair the ceramic diffuser will render the guarantee null and void
• Any defect should be reported within three days by fax or email to Dryden Aqua. The goods should be returned to Dryden Aqua or an official representative of Dryden Aqua, along with a written report on the circumstances leading up to the defect. Cost of returning the goods to be born by the purchaser.
• The purchaser certifies acceptance of the guarantee as set out.