Strainer Mesh & Sizing Reference

Mesh size, micron rating, and perforation diameter all describe the same thing — how big a particle a strainer screen lets through — but they're three different measurement systems, and spec sheets mix them freely. This page is a working reference: mesh-to-micron conversion, typical perforation sizing, what ranges are actually used for pump protection versus instrument protection, and the two concepts (open area and cleaning interval) that determine whether the strainer you specify actually performs the way the table suggests.

Mesh Count, Micron, and Perforation — How They Relate

"Mesh" counts the number of openings per linear inch of woven wire screen — a 100-mesh screen has 100 openings per inch. Micron rating describes the actual opening size in microns (millionths of a meter), which is the more precise, size-based way to talk about capture. Perforated metal — used in place of woven mesh for coarser, higher-flow-tolerant applications — is instead specified by hole diameter, usually in fractions of an inch, because at coarser sizes a "mesh count" description stops being meaningful.

The table below gives standard, published approximate conversions between US mesh count and micron opening size. These are widely available reference values (based on US Standard Sieve series openings) — actual opening size varies slightly by wire diameter and weave, and Tyler mesh numbers differ slightly from US mesh numbers at the same nominal count, so treat this as a working approximation, not a certified spec.

Perforated Metal Sizing (Coarser, Higher-Flow Applications)

For larger pipe sizes and higher flow rates, especially on raw water or wastewater duty carrying larger solids, perforated metal baskets or cartridges are more common than fine woven mesh — the round or slotted perforations resist plugging better than fine mesh at high solids loading, at the cost of coarser capture.

Typical Mesh Ranges: Pump Protection vs. Instrument Protection

What's downstream of the strainer determines how fine the screen needs to be — finer isn't automatically better, because finer mesh loads up faster and adds more pressure drop at the same flow rate.

Open Area: Why Finer Isn't Automatically Better

"Open area" is the percentage of a screen's total surface that's actually open to flow. A woven wire mesh generally offers a higher open-area percentage than perforated metal at a comparable opening size, because the wire itself takes up less surface than the solid metal between perforations. Within either system, finer openings mean less open area for the same physical screen size — which means higher pressure drop and faster loading at a given flow rate, even before any debris accumulates.

This is the concept that should override "just spec the finest mesh available" thinking: a screen that's too fine for the flow rate and solids load will pressure-drop and plug faster than a correctly matched coarser screen, even though it captures smaller particles. Sizing the strainer body one pipe size larger than the line, when practical, helps offset this by increasing total screen surface area — more open area at the same mesh rating, and a longer interval between cleanings.

Cleaning Intervals — the Concept, Not a Fixed Schedule

Cleaning frequency shouldn't be a fixed calendar schedule; it should be driven by differential pressure (delta-P) across the strainer. As debris accumulates on the screen, pressure drop across the strainer climbs above its clean baseline. The generally accepted approach is to monitor pressure on both sides of the strainer (or use a differential pressure gauge or switch built for the purpose) and clean or blow down once the differential reaches the threshold specified in the manufacturer's data — commonly cited rule-of-thumb ranges in general industry guidance run around 5–10 psi above the clean baseline, but that number varies by strainer design and application, so confirm the actual threshold for your unit rather than relying on a rule of thumb alone.

A strainer with a blowdown connection makes this a low-effort routine task; without one, cleaning means isolating the line and physically removing the screen — plan accordingly on any application where you expect regular sediment loading.

Frequently Asked Questions

What mesh size do I need for general water service?

For a centrifugal pump on general water duty, 20–40 mesh is a common starting range, but the correct answer depends on the pump manufacturer's own recommendation and what's downstream. Send us the application and we'll help confirm.

Is a finer mesh always better protection?

No. Finer mesh has less open area, which means higher pressure drop and faster loading at the same flow rate. Match the mesh to what's actually downstream, not to "as fine as possible."

How do I know when to clean or blow down a strainer?

Watch differential pressure across the strainer rather than the calendar. Clean or blow down once pressure drop reaches the threshold in the manufacturer's data — commonly in the 5–10 psi range above clean baseline as a general rule of thumb, though the exact number is design-specific.

What's the difference between mesh and perforated screening?

Mesh is woven wire, described by openings per inch; perforated metal is solid sheet with punched holes, described by hole diameter. Perforated screening is more common at coarser capture sizes and higher solids loads because it resists plugging better than fine mesh in that service.

Related Guides

• Y Strainer vs. Basket Strainer
• Swing Check Valve Guide
• Check Valve Types Compared
• Check Valve Orientation & Installation
• Buna vs. Viton Check Valve Seats

Strainers in Stock

• 1 in. Brass Wye Strainer (940525)
• 3 in. Ductile Iron Wye Strainer, Flanged (9642FL3)
• 6 in. Ductile Iron Wye Strainer, Flanged (9642FL6)
• 1-1/2 in. Ductile Iron Wye Strainer, Threaded (9642TH07)
• 3/4 in. Brass Ball Valve with Strainer (947134)

Published performance data is general engineering reference, not a certification for your application. Confirm specifics against the manufacturer datasheet or ask us.