There are two essential values to maintain for successful automatic screen filtration at a given flow rate and micron rating: Enough pressure, enough screen area. These values are most critical at the finest filtration degrees -- 10 micron above all, but also true for 18 and 25 micron.
Those of us on the supply side of filtration are responsible to size correctly in response to an engineer advising micron degree, incoming pressure and max flow.
The imperative of providing total screen area sufficient to assure successful filtration is often underestimated. But it's no less important than adequate wing surface area is to achieve flight. (The two principles are very much related.)
One of the key advantages of Omicron solutions against any competitor in the market is the sheer size of screen area we provide within our housings. Even though the housings are not that much larger than a competitor's, the use of internal space is vastly more efficient, which allows us to maximize the available screen area within.
Here's an easy way to understand the differences. Our models, like a competitor's, are identified by total cm² of screen area. See below, from small to large:
Competitor | 1500 | 3000 | 4500 | 6000 | |||||
Omicron | 5300 | 8000 | 10600 | 13200 | 16500 | 21300 |
It's apparent that an "alternative" manufacturer's largest filter (6000 cm2) has about the same capacity as our smallest (5300 cm²). Their largest duplex system -- 2x 6000 (= 12,000 cm²) -- actually has less capacity than our mid-size simplex 13200.
Our largest unit with 21,300 cm² of screen area has more than 3.5 times the capacity of that company's largest (only 6000 cm²).
Note: Duplex and triplex manifolds are available for flow rates that exceed the capacity of simplex units.
Now check out this photo of three Omicron systems nearing completion at the factory. It tells a lot.
At foreground left you'll see a duplex 5300 system, thus 10,600 cm2 of total screen area.
An Omicron 5300 is the smallest unit we offer for new construction or retrofit projects -- with about as much screen area as the largest model (an SAF6000) another distributor considers adequate for high flow rates..
At foreground right you'll see our most often specified solution for 400 gpm @10 micron: Omicron Twin 16500 -- thus 33,000 cm2 screen area for 400 gpm. That is the capacity required for today's projects calling for flow rates in the 300 - 400 gpm range @10 micron.
At center you'll see an even larger solution with 42,600 cm2 of screen area, indicated for higher flow rates, or simply for greater capacity to manage highly turbid water conditions.
For the project on the left, the engineer originally specified an Amiad duplex SAF4500, 20 micron. The awarded contractor realized he could offer the owner a larger capacity Omicron Twin 5300 for less money. (The owner was pleased, too.)
For the project on the right, that other vendor apparently thought that 9000 cm2 @10 micron, with street pressure less than 40 psi, would be just fine for 400 gpm supplying a midtown luxury hotel project. Once the actual operating conditions were fully reviewed, the engineer and owner took exception. The specification was rewritten for Omicron Twin 16500-10(H) PN25 316L.
Underway at center is a retrofit application for a 60-story Brooklyn residential building that had suffered severe brown water conditions ever since it opened. Although the MEP firm initially thought 9000 cm2 of screen area @20 micron would be adequate, the building engineer understood the advantage ownership would gain in acquiring a much larger and finer (10 micron) solution: Omicron Twin 21300-10(H) 316L.
Below are more examples of solutions the distributor originally offered as viable which, after evaluation by engineers or owners, were rejected in favor of much larger Omicron filters. Note in particular the vast difference in cm2 of screen area per gpm. That is the essential value to pay attention to.
Incoming Max Flow / Pressure |
Their proposal |
Revised to Omicron |
Project 1 |
12,000 cm² screen / |
33,000 cm² screen / 10 micron relocated to downstream of house pumps to leverage high pressure |
Their cm² per gpm: 30 | Our cm² per gpm: 83 | |
Project 2 |
9000 cm² screen / |
33,000 cm² screen / 10 micron relocated to downstream of house pumps to leverage high pressure |
Their cm² per gpm: 23 | Our cm² per gpm: 82 | |
Project 3 |
12,000 cm² screen / |
33,000 cm² screen / 10 micron located downstream of house pumps to leverage high pressure |
Their cm² per gpm: 28 | Our cm² per gpm: 77 | |
Project 4 |
4500 cm² screen / |
42,600 cm² screen / 10 micron with booster pump to increase inlet pressure to 80 psi. |
Their cm² per gpm: 6.8 | Our cm² per gpm: 65 | |
Project 5 |
12,000 cm² screen / |
42,600 cm² screen / 10 micron relocated to downstream of house pumps to leverage high pressure |
Their cm² per gpm: 17 | Our cm² per gpm: 61 |
We presume that that in every instance the distributor assured decision makers their solutions would be reliable. Our 20+ years of direct field experience -- including with the very product line they are now promoting -- lead us to disagree.
One simple reason is this: New York City water has a far higher level of Total Suspended Solids (TSS) / Turbidity (NTU) than any major city in the US. The Turbidity (NTU) value of New York City water is routinely 1.2 NTU -- or higher. For reference, the term "city water quality" is generally understood to imply NTU not exceeding 1.0. There is an enormous difference between the concept of "city water" and actual NYC water conditions.
When we size filtration for a NYC application, we are guided by the empirical reality of presenting water conditions. (Not, for example, what a piece of sales literature or an animated video clip might suggest is good enough.) There is no substitute for the judgment that derives from many years of direct experience.