How to Choose Between Butterfly and Gate Valves for Water and Wastewater

Quick Answer

  Choose a butterfly valve when you need compact size, lower cost in large diameters, fast operation, or occasional throttling in DN≥200 water & wastewater lines.

  Choose a gate valve when you need tight isolation, minimal pressure loss when fully open, bidirectional sealing, and compatibility with scraper/cleaning pigs (where applicable).

Core Differences at a Glance

When to Use a Butterfly Valve

Pick butterfly valves if you need:

  ● Compact installation in pump rooms or galleries with tight space.

  ● Cost efficiency at large diameters (DN≥300), with lower actuation torque and simpler gear/electric packages.

  ● Occasional throttling (e.g., double-eccentric design reduces wear and torque).

  ● Fast open/close to isolate branches or equipment.

  ● Lower structural loads on pipe supports and slabs.

Best-fit scenarios

  ● Municipal water & wastewater distribution lines (PN10/PN16).

  ● WWTP processes: inlet/outlet isolation, aeration headers (check material/liner compatibility).

  ● HVAC & building services: chilled/cooling water.

  ● Fire protection (when specified): indicator-types or monitored actuated sets, per local codes.

Explore our ranges: Wafer Butterfly Valves / Lug Butterfly Valves / Flanged Butterfly Valves: https://www.yaxing-valve.com/butterfly-valve/

When to Use a Gate Valve

Pick gate valves if you need:

  ● Full-bore, minimal headloss in the open position.

  ● Bidirectional, drop-tight isolation and long service intervals.

  ● Compatibility with pigging/cleaning (project dependent).

  ● Established specs (AWWA C509/C515, BS 5163, DIN 3352) in waterworks tenders.

Best-fit scenarios

  ● Trunk mains / transmission lines where pressure loss is critical.

  ● Critical isolation at plant boundaries or between zones.

  ● Fire loops where spec calls for OS&Y/NRS gate valves with supervisory switches.

Selection Checklist (print-friendly)

  ● Line size & PN: DN? PN10 or PN16 (or higher)?

  ● Available space & weight: center-to-face, actuator envelope, lifting limits.

  ● Pressure loss tolerance: compute ΔP vs pump curve and energy cost.

  ● Operation mode: open/close only or throttling duty? frequency?

  ● Media & temperature: potable water, wastewater solids, chemicals? seat/liner compatibility.

  ● End-of-line / single-ended maintenance: lug butterfly or gate?

  ● Actuation & control: manual, gear, pneumatic, electric; feedback/positioning.

  ● Standards & documents: EN/AWWA, EN 12266-1 testing, MTC, coating reports.

  ● Lifecycle cost: valve + actuator + energy + maintenance.

  ● Lead time & spares: standard trims in stock? seat kits, stem seals, gearboxes?

Send the checklist with your RFQ → we’ll return a configured BOM. Request a Quote

Engineering Notes

Pressure Loss & Energy

  ● Gate valves offer the lowest ΔP fully open.

  ● Butterfly valves have slightly higher ΔP but often negligible at low/moderate velocities; the smaller footprint and lower actuator torque may offset lifecycle costs.

Throttling

  ● Prefer double-eccentric (double-offset) butterfly valves for intermittent throttling; avoid throttling with resilient-seated gate valves (accelerated wear).

End-of-Line (EOL) Service

  ● Lug-style butterfly valves can be used EOL (check PN and manufacturer limits).

  ● Wafer butterfly valves are generally not rated for EOL.

  ● Gate valves are commonly suitable for EOL isolation (confirm with spec).

Standards Reference (quick)

  ● Butterfly: EN 593; AWWA C504.

  ● Gate: AWWA C509/C515; BS 5163; DIN 3352.

  ● Testing: EN 12266-1 hydrostatic & seat tests.

Common Mistakes (and how to avoid them)

  ● Using wafer butterfly at pipe ends → choose lug or flanged designs.

  ● Specifying throttling with resilient-seated gate valves → use double-eccentric butterfly.

  ● Ignoring actuator torque margins → size against real ΔP + safety factor.

  ● Mismatching PN/flange drilling → verify EN 1092-2 PN10/PN16 patterns.

  ● Overlooking media compatibility → pick EPDM/NBR seats appropriately; consider coatings for potable water.

FAQ

Q1. Which valve has lower pressure loss?
A. Gate valves are full-bore and have the lowest ΔP when fully open. Butterfly valves are low to moderate ΔP depending on disc and velocity.

Q2. Can butterfly valves be used for throttling?
A. Yes—prefer double-eccentric designs for intermittent throttling; avoid throttling with resilient-seated gate valves.

Q3. Is wafer butterfly suitable at the end of a line?
A. No. Use lug-style butterfly valves (or flanged) for end-of-line service.

Q4. What should I include in an RFQ?
A. DN/PN, medium/temperature, required standard (EN/AWWA), end-connection, duty (on/off vs throttling), actuator type, quantity, delivery window, documents (MTC, EN 12266-1 tests).