Metering technical information

Pressurized systems

The term “pressurized” refers to any system in which liquid flows through a pipe. Water is typically (but not always) pumped directly into a pipe in a closed and pressurized system.

Examples of pressurized pipe measuring devices

Mechanical — propeller, positive displacement, or turbine
Electronic — electromagnetic (i.e., insertion or full pipe), ultrasonic, or vortex

• Liquid Flowmeters - A Guide for Selecting a Flowmeter for Pressurized Systems
• The Basics: How to Read Your Mechanical Meter 

Metering requirements for pressurized systems

• WAC 173-173-100 — What are the specific requirements for meters for pressure systems?,
• WAC 173-173-110 — What are the installation requirements for meters on pressure systems?
• WAC 173-173-120 — What are the operation and maintenance requirements for meters on pressure systems?

Open channel systems

The term “open channel” refers to any system in which liquid flows with a free surface, such as canals or irrigation ditches.

Examples of open channel measuring devices

Weirs — sharp crested (v-notch, rectangular, or Cipoletti)
Flumes — long-throated or Parshall
Submerged orifice
Electronic methods — Doppler, electromagnetic, anemometer and propeller velocity, optical strobe

• Guidelines for Selecting Open Channel Meters
• Inspecting an Open Channel Water Measuring System
• The Basics: How to Read Your Meter (mechanical meters)

Metering requirements for open channel systems

• WAC 173-173-130 — What are the specific requirements for measuring systems on open channels?
• WAC 173-173-140 — What are the installation requirements for open channel measuring systems?
• WAC 173-173-150 — What are the operation and maintenance requirements for open channel measuring facilities?

Meter vendors and installers

WAC 173-173 lays out the requirements for installing meters. If you are responsible for reporting your water use, you must also ensure you have an approved measuring device installed or constructed in accordance with the manufacturer’s and/or designer’s specifications. This applies to both pressurized systems and open channel flows.

If you are unsure of the manufacturer’s specifications, you may consider hiring a professional vendor within your service area to install your meter. Examples of professional services that may sell or perform meter installations include (but are not limited to):

• Pipe and pump companies
• Irrigation specialists
• Instrument supply shops
• Water specialty companies
• Electric instrumentation supply