Jul 07 2014

introductionCombination Cold Water Meter classification, main control parameters and the implementation of standards

Water meter according to the medium temperature can be divided into cold water and hot water meter, water temperature 30 ℃ is the dividing line between the cold water meter: medium lower temperature is 0 ℃, the upper limit temperature is 30 ℃ water meter.

Combination Cold Water Meter

The main control parameters of cold water meter was chosen for water flow, flow, flow, overload, minimum flow boundary flow, nominal pressure, the maximum allowable working pressure, pressure loss.

Cold water meter main classification:

According to the different ways into the installation: horizontal, vertical water meter cold water meter.

According to the wing wheel structure is divided into: Woltman water meter, rotor type water meter.

In accordance with the immersion method counting machine is divided into: dry wet water meter, Combination Cold Water Meter.

Selected points:

1), water meter selection must first consider the water meter working environment: such as water temperature, working pressure, time, measurement range and the water quality of water were selected, then press through the design of flow meter, water meter pressure loss to produce close to and do not exceed the specified value to determine the water meter diameter. In general, nominal diameter less than DN50, should use the rotor type water meter; nominal diameter is more than DN50, should use the spiral wing type water meter; flow meter should be used when the variation range of compound water meter.

2), nominal diameter less than DN50 of the water meter, should according to the water supply system design flow using.

3), should be preferred dry water meter. In the non heating area specified by the state, and extreme minimum temperature below -4 ℃, indoor public part of the household water meters or adjacent to the northwest side wall should be used dry water meter, water meter. Such as the use of wet water meter should do heat preservation.

Edit the construction, installation points

1) General requirements

(1) the water should be easily accessible for reading (for example, do not use a mirror or a ladder), assembly, maintenance, disassembly and necessary “in situ” removing mechanism. In addition, on the quality of more than 25kg of the water meter shall be unhampered access to the installation site, so that the water meter can be attached to its working position or removed and the surrounding in the working position to provide appropriate space to install the lifting device and should consider the following points:

Need proper lighting installation location;

The floor should be no obstacles, and even hard and not slip.

(2) in all cases, especially in the table wells installed water meters off the ground, application of high enough to install water meters and fitting method to avoid contamination. When necessary, the table well should provide a clarifier or gutter drainage.

2) installation requirements

(1) the water meter should prevent to cause damage risk by the installation place around impact or vibration.

(2) the water cannot be caused by excessive stress of pipe and fittings. When necessary, the Woltman Type Bulk Water Meter should be installed in the base or carrier. In addition, the upstream and downstream should be properly fastened on one side, to ensure open or discharge water table, not by the stem the impact of water facilities for the moving parts

(3) the water meter should prevent the risk of damage caused by the limit temperature of water and the surrounding air.

(4) the water meter should prevent flood and rain.

(5) the water direction should be in conformity with the type.

(6) the water meter should prevent damage danger caused by external environmental corrosion.

(7) should always comply with the use of water as the ground of effective national laws and local regulations. The water meter as an electrical ground parts, in order to minimize the risk of operating personnel, the water meter and the connection bypass pipe should be permanent.

(8) in order to prevent the hydraulic conditions unfavorable (cavitation, surge and water hammer) caused water damage, preventive measures should be taken to.

(9) when necessary, measures should be taken to avoid sudden changes, close to the water meter flow section.

(10) spiral wing type water meter (also known as v Manchester meter) special installation requirements: the water meter disturbance on the upstream flow is sensitive, which cause large error and early wear. Flow under two types of perturbation velocity distribution and vortex distortion. The typical velocity distortion is caused by partially blocking the tube disorders, such as some closed valve, but this effect can be easily reduced to a minimum. The vortex is mainly caused by two or more elbow on different planes, this effect can be used to ensure the water upstream straight pipe have long controlled; if this is not possible, then install a straightening device.

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