overview

Glass rotor flowmeter (hereinafter referred to as flowmeter) is one of the instruments used to measure the flow rate of single-phase media such as non turbid liquids and gases. This instrument has the advantages of simple structure, easy maintenance and use, and low price. Mainly used in chemical, petroleum, light industry, medicine, fertilizer, chemical fiber, electricity, metallurgy, food, sugar, fuel, papermaking, environmental protection and scientific research departments.

Working principle and structure

The measuring part of the instrument consists of a vertically installed glass cone tube and a float inside the tube. The large end of the cone tube is upward, and the float moves up and down along the axis of the cone tube with the flow rate. When the fluid passes through the conical tube from bottom to top, a differential pressure is generated on the upper and lower end faces of the float due to the action of the fluid, and the float rises under this differential pressure. When the upward force acting on the float is equal to the combined force of gravity, buoyancy, and viscous force acting on the float, the float stabilizes at a certain height. At this point, the height of the float in the cone tube corresponds to the flow rate it passes through. This height is a measure of traffic volume.

Main features:

• Simple structure and reliable performance
• Low pressure loss
• Superior flow regulation performance
• Special design facilitates improved performance

Technical parameters:

orifice： DN4～100

measuring rangeWater (20 ℃) 1L/h~100m3/h

Gas (101325Pa, 20 ℃) 16L/h~3000m3/h

Range ratio： 10∶1

accuracy classLevel 1.5, Level 2.5, Level 4, Level 6

nominal pressure： DN4~10 1.0MPa

DN15~50 0.6MPa

DN80~100 0.4MPa

operation temperature：≤ 120℃

Connection methodFlexible hoses, metal pipes, flanges (GB/T9119-2000)

Installation and use

1. Installation

(1) Before installing the instrument, carefully inspect whether the glass tube is damaged, and remove the filling material to prevent the float from jumping. Check whether the float can slide freely up and down.

(2) The flowmeter must be installed vertically on the pipeline (with the large end of the cone facing upwards), with the flow direction from bottom to top. The pipeline system for installing flow meters should have sufficient rigidity, and strong twisting of the flow meters should be avoided during installation.

(3) For the convenience of observation and maintenance, sufficient space should be left during installation.

(4) If there is backflow in the pipeline, especially when there is water hammer, a one-way check valve should be installed after the downstream valve of the flowmeter to prevent damage to the flowmeter. For the convenience of inspection, maintenance, replacement of flow meters, and cleaning of pipelines, it is recommended to install bypass pipes according to Figure 5.

(5) When the measured fluid contains large particulate matter or is dirty, a filter should be installed upstream of the flowmeter.

(6) When the fluid being measured is a pulsating flow, causing the float to fluctuate and unable to measure, a buffer or setting device of appropriate size should be installed upstream of the flowmeter to eliminate pulsation.

(7) When measuring gases, in order to ensure stable operation of the instrument, the pressure at the outlet of the flowmeter should not be too low. The valve upstream of the flowmeter should be fully opened, and the flow rate should be adjusted using the valve downstream of the flowmeter, and this valve should not be too far from the outlet of the flowmeter.

2. Use

(1) When using a flowmeter, the upstream valve should be slowly opened to full open, and then the downstream valve should be slowly opened to regulate the flow. When stopping work, the upstream valve should be slowly closed first, and then the downstream valve should be closed. If the float does not rise after opening the valve, the valve should be closed to find the cause and reopened after the fault is resolved.

(2) During use, if the float is found to be stuck, do not use any tools to strike the glass cone tube. You can eliminate it by shaking the tube or disassembling the tube.

(3) During use, if the measured fluid is found to overflow from the sealing part of the glass tube, simply remove the front and rear covers and tighten the gland bolts until no overflow occurs. If the above methods do not work, it is generally due to the failure of the sealing packing.

(4) If the cone tube and float are contaminated, they should be cleaned in a timely manner.

(5) If the working diameter (reading edge) of the float is damaged or worn, it should be recalibrated.

(6) When the state of the measured fluid (density, temperature, pressure, viscosity, etc.) is different from the scale state of the flowmeter, the indication must be corrected.