Disc Diffuser Specification Guidelines

Disc diffusers are an excellent way to deliver aeration for many wastewater facilities.

For maximum benefit owners and engineers must make a decision between 2 competing philosophies.

Do I want the cheapest system? 
Do I want a value system with defined quality?

All diffuser systems are sold under one of those 2 specifications!

EDI only offers value designs presenting quality first systems for maximum value and lowest cost of ownership. To assure you get a quality system a few key items MUST be specified. Without these quality specifications, the CHEAPEST vendor sells the equipment and the customer is disadvantaged. EDI has outlined features that engineers and owners can specify to assure quality. These items are nonproprietary and any manufacturer can supply this level of quality if required with proper specification. All engineers and customers want competitive and low cost pricing so establish quality level first then everyone will compete for lowest cost of specified quality!

For quality competition, the following disc diffuser items MUST BE SPECIFIED:

• All air piping to be sized based on air flow and pressure loss. This allows air laterals to be properly sized at 3” Ø up to 8” Ø based on air volumes handled.
• All air piping and diffuser piping MUST be standard IPS sizes. 3” pipe to be 3.5” OD and 4” pipe to be 4.5” OD so local standard piping components can be purchased or employed in maintenance or repair WITHOUT special piping available only from the aeration system vendor.
• Heavy wall piping for long term service. Piping of SDR 26 or schedule 40 IPS for all PVC piping.
• Minimum of 2 year warranty on defects of materials and workmanship. EDI recommends specification of 5 year warranty.
• Connections – All air laterals (diffuser pipe) shall have rigid positive flange connections that allow infinite adjustment for leveling the diffuser. Note: Coupling connections with teeth are not so strong and can fail easily. In addition, the construction with the anti-rotation teeth only allow angular movement in 3° to 5° increments – Hard to level all piping.
• Diffuser head mounting capable of withstanding vertical edge loading of at least 300 pounds. This connection is critical for long life.
• Stainless steel or nonmetallic diffuser supports are acceptable. All pipe supports to be smooth to prevent accumulation of rags. Pipe supports to eliminate sharp edges. Threaded rods extending more than 1” exposed shall have safety caps installed.
• Standard TiO2 concentrations in PVC pipe as recommended by US Plastic Pipe Institute. (Note: Special 2% TiO2 specifications were developed by one manufacturer because of the thin PVC pipe they supply unless items 2 & 3 are specified.) Full 2% TiO2 offers no benefit to customer with about 10% cost increase to favor a manufacturer with weak pipe design.

Diffuser unit to be specifically engineered for use with membrane diffusers.

• Shall have a flat support base under membrane with check valve capabilities, systems with plenum body shall not be considered.
• Diffuser head can be either solvent welded to piping or shipped with membrane installed and boxed for field mounting of full factory assembled saddle mount head. Heads diffuser factory installed must have membranes field installed to protect from sunlight or mechanical damage until ready for use.
• Spare Diffuser Heads - NO spare diffuser heads to be installed. With membrane diffusers, you benefit with maximum number of units in operation at any air flow. Spare units cost money and no immediate benefit. Units installed and operated from day one, will save energy and be useful immediately. This is a unique benefit of membrane diffusers vs. ceramic which must have a high air flow. Recommend install as many units as possible. If any spares, have them boxed and in premium condition to add when needed.
• High temperature resistance with CPVC or glass filled polypropylene units with CPVC piping and/or components which offer maximum system protection.
• Purge location at drop pipe to remove water as soon as air is applied to system. Purge assembly to use air subheader as reservoir for moisture and superior pumpage.
• All piping to have fixed support at beginning of run with slide or simple supports for all other supports on each run. This allows free expansion/contraction with low stress. Do not connect ends of lateral piping into closed loop because of major structural stress induced and NO functional value.
• All pipe supports or hold down mechanisms to have at least 2” wide contact area 360 degrees around pipe to minimize pipe stress and pipe deflection.
• Diffusers and piping system shall be manufactured in USA for reliable long term service. Note: Saddle mounted units allow diffusers and membranes to be boxed and protected from damage by sunlight, mechanical, or handling. Boxed units with factory installed membranes can be mounted on pipe much faster than membranes can be installed in the field. All boxed unit membranes are fresh with maximum performance and life. Factory mounting of membranes eliminates multiple tank draining to tighten or seal membranes.

OPTIONS: Items that can be specified if premium EDI disc diffuser systems are to be preferred or favored by the detail specification.

Only saddle mounted units to be used to allow addition/subtraction of units or reconfiguration for process control. Note: Saddle mount units also offer unique opportunities for use with metal or special pipe materials.

Premium SuperStrut™ pipe support features offer major advantages:

• Nonmetallic maximum corrosion resistance.

• Sheds rags.

• Safe for personnel.

• Installs in 40% of the time.

• Easy removal of any pipe segment.

• Strongest support in the industry.

• EZ™ seal membrane feature to allow quick easy membrane installation, prevent leaks, and leak maintenance.

• KliKlock™ saddle mount units for best installation speed and security.

• Optional stainless steel piping with special saddle mounted 8P to 12P diffuser assemblies.

• Optional ModuleAir™ or floating module disc diffuser systems for retrievable installations in basins or lagoons.