What is ROF (Rate of Flow) Indicator?

A ROF (Rate of Flow) Indicator is an instrument used in a water treatment plant to measure and display the quantity of water flowing through a pipe, channel, or system over a specific period of time.

In simple words, it tells you how fast water is moving inside the plant.

Flow is usually measured in:

• Liters per second (LPS)

• Cubic meters per hour (m³/hr)

• Gallons per minute (GPM)

• Million liters per day (MLD)

ROF indicators help operators maintain proper flow levels during processes like coagulation, sedimentation, filtration, and distribution. If the flow is too high or too low, treatment efficiency can be affected.

Modern ROF indicators may use:

• Mechanical flow meters

• Electromagnetic flow meters

• Ultrasonic flow meters

They often connect to SCADA or PLC systems for real-time monitoring and automation.

What is LOH (Loss of Head) Indicator?

A LOH (Loss of Head) Indicator is a device used to measure the pressure difference (head loss) between two points in a water treatment system, usually across a filter.

When water passes through filter media like sand or gravel, resistance builds up due to trapped dirt and particles. This resistance creates a pressure drop. The LOH indicator measures this pressure drop.

In simple terms, it tells you how much resistance the water is facing while flowing through the filter.

LOH indicators are mainly used to:

• Monitor filter performance

• Determine when backwashing is required

• Prevent overloading of filters

• Protect plant equipment

They typically use:

• Differential pressure gauges

• Manometers

• Digital pressure transmitters

In Short

• ROF Indicator = Measures how much water is flowing.

• LOH Indicator = Measures how much resistance (pressure loss) the water experiences.