Flap-type (Sight) flow indicator

Mechanical. Indestructible. The high durability solution – specially suitable for cloudy and opaque media

In modern plant engineering, extremely robust and reliable devices are generally required for displaying current values and flow monitoring. Flap-type flow indicators impress with maximum reliability. A flap-type flow indicator offers good measurement results with smooth functionality in plant engineering. Flap-type or sight flow indicators – or simply flap indicators – are used to measure clear and opaque liquids easily. In addition to this, an optional inductive contact also makes flow monitoring possible in the measurement indicator.

Flap flow indicators by MECON

Measurement principle for flap-type or sight flow indicators

Flap-type or sight flow indicators work based on the simple flap principle: The measurement flap (2) in the fitting (1) rotates around an axis (3). If there is no flow, the deadweight closes the flap automatically in the pipeline. When liquids are flowing, the flap is raised based on the flow speed. The respective flow quantity can be read directly from the flap position in clear, transparent liquids. The lower flap edge is always the reading edge. If the flow is of cloudy and opaque liquids, a magnet (5) attached to the flap transfers the motion of the flap to a mechanical indicator (8) on the outside. That allows the flow to be shown on the scale. The scale and the indicator themselves are protected against external effects and soiling by a pane. As standard, the scale is in m³/h and is calculated based on the measurement substance specified by the customer in the required operating data, pressure and temperature, where the density deviates from 1 kg/l (62.43 lb/cu.ft). An inductive contact can be actuated via a contact tab fitted on the indicator.

Structure of the flap flow indicator

In their basic form, flap-type flow indicators are based on a fitting and a measurement flap that is mounted to rotate around an axis. In the idle condition (i.e. no flow), the flap seals the pipeline due to its own weight. As soon as liquids are flowing, the flap is raised based on the flow speed. The respective flow rate can be read directly from the position of the flap in clear liquids. The lower edge of the flap is the reading edge.

Advantages of flap flow meter:

• Very robust design
• Suitable for clear and cloudy liquids
• Vertical and horizontal installation possible
• Practical, low-maintenance design
• Largely not affected by viscosity
• Suitable for liquid temperatures up to max. +100°C
• Inductive contact for flow monitoring (optional)

Flap-type or sight flow indicators are used in a wide range of industries worldwide:

• Building services equipment, air conditioning and heating technology
• Chemicals
• Plant and mechanical engineering
• Water and wastewater