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Water well screen calculator

The well screen calculator sizes a water well screen from the well yield, screen diameter, slot and wire profile. It returns the open area per metre, the entrance velocity and the minimum screen length that keeps entrance velocity at or below the commonly used 0.03 m/s, taking half the open area as effective.

Allows for slots blocked by the filter pack.
Gives an indicative slot.

Entrance velocity0.017 m/s

At or below 0.03 m/s

Open area
31.3 %
Open area per metre
0.1963 m²/m
Minimum length at 0.03 m/s
3.4 m
Indicative slot from D10
Enter D10

OA = S / (S + W). Open area per metre = pi x D x OA. v = Q / (OA per metre x effective % x L). Minimum length = Q / (0.03 x pi x D x OA x effective %).

Assumes the commonly used design limit of 0.03 m/s and 50 % effective open area (editable). Indicative only; screens to IS 8110:2019 are confirmed by SIMO engineering.

Send this to an engineer

Your inputs and results go into the quote form, so an engineer can check them against your operating conditions.

How the well screen calculator works

The calculator checks a water well screen against the entrance velocity commonly used in design and gives the shortest screen that meets it.

  1. Open area fraction: OA = S / (S + W), from the slot S and the profile wire width W.
  2. Open area per metre of screen: pi x D x OA, where D is the screen outer diameter in metres.
  3. Effective open area: half of the open area by default, because filter pack grains block part of each slot. The assumption can be changed to the design factor of the project.
  4. Entrance velocity: v = Q / (effective open area per metre x screen length), with Q in cubic metres per second.
  5. Minimum screen length for 0.03 m/s: Q / (0.03 x pi x D x OA x 0.5).

If the filter pack D10 is entered, the calculator suggests a standard slot at or just below it. The suggestion is indicative, and the slot is confirmed from a sieve analysis.

Worked example

A well yielding 36 cubic metres an hour (0.01 cubic metres a second) with a 200 mm screen, a 1 mm slot and 28SB wire (2.2 mm):

  • OA = 1 / 3.2 = 31.25 percent
  • Open area per metre = pi x 0.2 x 0.3125 = 0.196 square metres
  • Effective open area per metre at 50 percent = 0.098 square metres
  • With 6 m of screen, entrance velocity = 0.01 / (0.098 x 6) = 0.017 m/s, within 0.03 m/s
  • Minimum length for 0.03 m/s = 3.4 m

SIMO water well screens are made to IS 8110:2019. The water well screen design guide covers slot selection, and the water well screen page describes the range.

Questions

Common questions

What entrance velocity should a well screen have?

A widely used design limit is about 0.03 m/s (3 cm/s) through the effective open area. Keeping below it limits sand movement, encrustation and head loss across the screen and the filter pack.

Why does the well screen length calculator assume 50 percent open area?

Filter pack grains block part of each slot, so designers commonly take about half the calculated open area as effective. The figure is editable, so a client's own design factor can be used instead.

How do I choose the well screen slot size?

With an artificial filter pack, the slot is usually set to retain about 90 percent of the pack, which is close to its D10 size. A sieve analysis of the formation or the pack is the starting point.

Are SIMO water well screens made to IS 8110?

Yes. SIMO water well screens are made to IS 8110:2019, with weld rings, threaded ends and bottom plugs supplied as standard end connections. Share the yield, diameter and slot with your enquiry.

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