What in the world is Delta P ( ΔP ) ?

So– what in the world is Delta P … and no we’re not talking about your old Fraternity or Sorority.  Actually in the world of filtration Delta P (ΔP) is a very commonly used term, Delta P or its symbol usually refers to the pressure drop across a piping component such as a valve or industrial filter.   The symbol for Delta “Δ” (yes, it’s the Greek symbol) represents the ‘change’ in something; in this case a change, or drop, in pressure (p).

To determine the Delta P across a valve or filtration system with pressure gauges, just subtract the outlet pressure (P2) from the inlet pressure(P1) … yes, it’s that simple.

Here is an Example:

Valve 1 = 60 PSI – Valve 2 = 58 PSI

ΔP = 2
For more helpful filtration tips, updates and the latest news from Eaton’s Filtration Business follow @AskFilterMan on twitter.



The higher the velocity, the higher the potential for shock loading.

Velocity plays an important role when recommending a Strainer for a piping system. The higher the velocity, the higher the potential for shock loading (water hammer). Typically for metal piping systems the most desirable range is between 6 to 1 0 feet per second. For plastic piping systems the maximum recommended flow rate is 8 feet per second.

Most end users won’t know the flow velocity in their systems, but they will know the flow in gallons per minute. To convert gallons per minute to velocity Ft./Sec. take the GPM  0.4085 divided by the inside diameter of pipe squared.

(GPM x 0.4085) ÷ (ID² in Inches) 

Note: The above calculation is for water only.  

Water Hammer and Pressure Loss Calculators

Did you know that Eaton’s Filtration Business offers free online calculators to help determine pressure loss and water hammer?

Water Hammer Calculator
Calculate the total pressure change due to a sudden shutting of a valve, or water hitting the end of a pipe with our Water Hammer Calculator

Pressure Loss Calculator – Other
Enter your Flow Rate, Cv value of the strainer, basket mesh size, gravity of your liquid and the viscosity of your fluid is SSU into our Non-Water Based Pressure Loss Calculator which will compute the pressure loss for liquids with a viscosity other than water.

Pressure Loss Calculator – Water
Enter your Flow Rate, Cv value of the strainer and the basket mesh size into our Water Based Pressure Loss Calculator  which will compute the pressure loss for water and liquid with water-lilke viscosity



AskFilterman: Can a Y-Strainer be used in a vertical line?

Since Y-Strainers are used for protection (not collection f debris) in pipeline systems where the amount of material to be removed is small, the can be installed either horizontally or vertically.
However, it is recommended that shut-off valves be installed and the screening element must be on the down side of the strainer – flow into the screen.

What is the best perforation or mesh size for my filtration application?

The question of which perforation or mesh lining size to use comes up regularly. The basic rule is to use the coarsest size which will
strain out the debris to be removed. Using a finer size perf or mesh than needed will only result in premature clogging. When in doubt about which
of two perfs or mesh sizes to use, it is best ‘to choose the larger. Size the openings for one half of the particle size to be removed.

We are often asked – “what type of strainer would we recommend for a particular service”?  The answer depends on the application.
For equipment “protection”, we would generally recommend a Y-Strainer or a Tee type Strainer (relatively clean service conditions). For
“collection” we would suggest a basket type (dirty line with lots of debris). Temporary strainers (cone or basket type) are generally used for line
start-up then removed and replaced by permanent strainers at a later date.

For more information or to speak with an Eaton sales representative contact Eaton Filtration today.

Quick Tip from AskFilterman: Strainers, Temperature and Pressure

Here is a quick tip from our very own Filterman:  Remember, there is a direct relation between temperature and presuure. As temperature goes up, the pressure the strainer can handle goes down! For more quick tips follow AskFilterman on Twitter today!