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Amiad vs. typical competitor, for engineers

A detailed comparison for engineers and developers.


SUMMARY:


  • Filtration screen Screen area, effective filtration area, type of weaving, quality and integrity of support.
  • Cleaning mechanism Efficiency of cleaning (velocity per square inch of the screen), flush flow rate during flush cycles, long-term mechanical stress to the bearings, exposure to abrasive materials.
  • Control system   Reliability and flexibility to accommodate special requirements of applications.
  • Filter housing Quality of materials and construction, ease of installation and maintenance.
  • Water consumption   Volume of water required for backwash flush.
 
DETAILS:

Filtration screen
  • What is the total surface area? The capability of removing high loads of particles is directly correlated to the screen surface area. The finer the filtration degree, the larger the surface area required.
  • What is the total effective filtration area (TEFA)? TEFA is reduced by the screen support area, and is therefore defined by the net total of unobstructed filtration pores in the screen. The TEFA of Amiad’s free-floating 4-layer screen is nearly double that of a permanently bonded or sintered screen.
  • Type of weaving Filtration quality and reliability are determined not just by the smallest dimensions of the screen pores, but the type of weaving. Two screens with a 25 micron pore size, but different weave type, do not provide equal quality filtration. Weave type also affects the overall strength and durabilityof the screen.
  • Quality of construction The material and strength of the screen and its support are a determining factor in the maximum pressure differential the screen can withstand without damage. Amiad's patented 4-layer screen provides protection of the internal fine screen, as well as external strength to accept a 225 psi differential.  No welding or sintering is used, since these processes weaken the fine screen by making it susceptible to tearing at the contact points.

Cleaning mechanism
The cleaning mechanism must ensure that the screen is 100% clean at the conclusion of every flush cycle. Key considerations:
  • The backflush velocity force created during the flush cycle is a function of (1) percentage of the screen actually being cleaned and (2) pressure differential between the filter vessel and atmospheric pressure. This force determines the filter cleaning efficiency. Because Amiad is electrically powered, its efficiency is unvarying even when operating at fluctuating operating pressures.  A hydraulically operated system will, by contrast, clean with variable speed and duration as determined by fluctuating pressures. 
  • Amiad's electrically powered technology does not require operation of a turbine or hydraulic motor, thus efficiently utilizes all available energy for cleaning.
  • Amiad’s suction scanner, electrically powered, ensures a minimal required flush flow rate. A hydraulic turbine demands a flush flow two to four times higher than Amiad’s electrically powered mechanism. This difference becomes ever more critical in lower flow applications, as the flush flow rate increases as a percentage of the forward (effluent) flow rate. (Subtract the flush flow demand from the forward, and the difference is all that is left to meet filtration demand.) 
  • Amiad’s slow, controlled movement of the cleaning mechanism increases system reliability and cleaning efficiency. Hydraulic filters rotate relatively fast and therefore are more likely to require frequent replacement of bearings and suction scanners.
  • Amiad’s new Spring Loaded Nozzles technology, by which the nozzles actually contact the screen, dramatically increases cleaning efficiency by preventing side flow into the nozzles. Side flow, inevitable when there is distance between nozzles and screen, compromises the integrity of the backwash process.  The finer the filtration degree, the more critical this factor becomes.
  • The Amiad suction scanner, including the arms connecting the nozzles to the shaft, is entirely fabricated from 316L stainless steel.

PLC control system…
  • activates the back wash cycle based on time or pressure differential across the screen. Timing as a back up to PD is critical when the application is subject to variable flow rates.
  • integrates with a BMS for operation or alarms.
  • automatically opens a by-pass valve upon system fault or power failure.

Filter housing
  • Amiad’s SAF series housing is fabricated using thick-walled carbon steel, with zinc phosphate preparation and epoxy coated polyester paint to prevent corrosion. Stainless steel is an available option, with an itemized cost add-on. Tekleen supplies all filters in stainless; thus more of their equipment cost is dedicated to material irrelevant to performance, and less to critical technology that impacts actual operation.
  • A small footprint facilitates flexibility in installation. Skid-mounting of the entire system is an available option.

Water Consumption
  • From an environmental perspective, using hydraulic power rather than electrical might appear to be an advantage.  But in actual water conditions, it is not.  Amiad requires the electrical power of only a ¼ hp motor operating on average less than five minutes / day, to achieve consistent performance and reliability in diverse, fluctuating water conditions.  In “best case conditions” competitor uses at least twice the amount of water for backwash as Amiad; the resulting larger volume demanded by competitor's equipment thus also requires collection tanks in the 100 – 500 gallon range. 

Information Center

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