How to select and install water meterThe system diagram below shows several applications for some of the more popular products from the Goldland range of water meters
In Diagram 1 water meters for both hot and cold water applications are shown. On both the hot and cold water systems a bank of single-jet water meters is depicted. This sort of configuration could be used when water consumption for individual flats or offices needs to be recorded. Pulse output meters, suitable for connection to a building management system or electronic remote readout, are also available. Also shown on the hot water system is a multi jet water meter, which is a class B meter, available in standard or pulse output versions. On the cold inlet side of the system meters from the Woltman range of large industrial and irrigation water meters are shown.
The Woltman combination meter is designed to register very low and very high flow rates by using a multi jet meter and a Woltman meter together, whilst the irrigation meter is designed to be very resistant to waterborne contamination and provide a good record of water consumption at high flow rates.
SECONDARY WATER METERS
Goldland Water Project Equipment Co.,Ltd.offers a comprehensive range of secondary water meters for domestic, commercial and industrial applications. Goldland can provide the ideal metering solution for every installation. Please contact the Goldland Sales Department for advice on the most suitable meter for your installation.
Water authorities supply primary charging meters. Secondary meters are used when the water from one primary meter is split between a number of users.
All meters are factory tested to ensure that they comply with the relevant class, which is marked along with the approval number on each meter.
|Nominal Flow Rate||Qn||The designation flow rate of the meter.|
|Maximum Flow Rate||Qmax||The highest flow rate at which the meter accuracy will be within the maximum permitted error.|
|Minimum Flow Rate||Qmin||The lowest flow rate at which the meter accuracy will be within the maximum permitted error.
|Transitional Flow Rate||Qt||The flow rate at which the maximum permitted error of the meter changes.|
|Maximum Permitted Error from Qmin to Qt||± 5%|
|Maximum Permitted Error from Qt to Qmax||± 2%|
WATER METER SELECTION
The following is some basic advice on how to select the correct water meter for a given application.
The size of the water meter
Water meters are sized on their nominal flow rate. This is called the Qn and is given in cubic meters per hour (one cubic meter is 1,000 litres of water). The water meters maximum flow rate is twice the Qn. 1. If the required flow rate is known then a water meter can be selected so that the required flow rate falls between the nominal and maximum flow rates. 2. If the flow rate is not known then it is generally safe to select a meter of the same nominal size (DN) as the pipework it is to be connected.
What class of meter is required
The class does not indicate the accuracy of the water meter but at what flow rate the meter meets the common accuracy figures. These are ± 5% at the meters minimum flow rate and ± 2% in the meters normal range (between Qt and Qmax) for cold water meters. The figures for hot water meters are ± 6% and ± 3% respectively. The higher the class of water meter the higher the accuracy at very low flow rates; Class D having the highest accuracy, and class A the lowest.
When deciding if a low flow reading is required it should be remembered that even a class A Qn 2.5 (a 3/4 " meter) will start to read, within its tolerance band, at a flow rate of 1.66 l/m (a basin tap will flow at between 6 and 10 l/m)
If all that is required is an overall indication of the amount of water used then a class A or B meter is sufficient (most Water Authorities use single and multi jet water meters as they maintain their accuracy for a long time). If the total of a number of secondary meters has to relate very closely to a master meter then a class C meter should be selected.
Wet, Liquid sealed or Dry dial
Wet dial meters are used for cold water applications where the meter is subject to climactic changes (e.g. a meter mounted outside a building but still protected from frost) which could cause condensation to form on the face of the dry dial meter making it difficult to read. Liquid sealed dial can keep long term service to read clearly. This should be balanced against the possibility of water borne contamination getting into the meter. The type of meter must be selected based on site conditions, but in all cases dry dial meters should be used in applications where the water quality is suspect, ie. contaminated or cloudy.
What meter type
This is also related to class, as certain classes are only available for certain types of water meter. Select the class that is required and then check for availability in the class approvals list below. Single and multi jet meters are quiet in operation and so are better suited for use in a flat.
Sizes available (Sizes are given in terms of the meters Qn, or nominal flow rate, in m 3 /h) When you have selected the type of meter you are interested in from the table below, please refer to the relevant sub-section in the following categories.
Water Meter Selector Chart
When ordering please ensure that the following site requirements are known, ie. cold or hot water, vertical (specify rising or falling supply) or horizontal installation, dry or wet dial, or pulse output version.
|Type||Class||Nominal Flow in m3/h||Dry Dial||Wet Dial||Liquid Sealed
|Cold Water||Hot Water||Pulse Version||Vertical||Horizontal|
|Single jet meters||A&B||From Qn 1.5 to Qn 10||x||x||x||x||x||x||x||x|
|Multi jet meters||A&B||From Qn 1.5 to Qn 15||x||x||x||x||x||x||x||x|
|Volumetric rotary piston meters||C||From Qn 1.0 to Qn 2.5||x||x||x||x||x||x|
|Woltman industrial meters||A&B||From Qn 15 to Qn 1500||x||x||x||x||x||>x|
1. Thoroughly flush the service line upstream of the meter to remove dirt and debris.
2. Remove meter spud thread protectors. NOTE: To protect the meter spud threads, store the meter with thread protectors in place.
3. Set the meter in the line. Install the meter in a horizontal plane, with the register upright, in a location accessible for reading, service and inspection. Arrows on the side of the meter and above the outlet spud indicate the direction of flow.
For isolation and removal purposes, it will be necessary to install the water meter with a bypass line going around the meter and isolation valves as shown on diagram 2, below.
4. Do not overtighten connections; tighten only as required to seal. Do not use pipe sealant or Teflon tape on meter
5. If meter is equipped with an electrical contacting head register, line up molded tabs on inside of reed switch with corresponding indentions of receptacle on face of meter. Insert reed switch and turn 1/4 turn to lock in place.
6. Tie black and red wires on opposite end of reed switch to corresponding black and red water meter wires on controller. Insulate connection with water-proof wrapping.
7. With upstream shutoff valve only:
Open shutoff valve slowly, to remove air from the meter and service line. Open a faucet slowly to allow entrapped air to escape. Close the faucet.
With both upstream and downstream shutoff valves installed:
To test the installation for leaks: Close the outlet (downstream) shutoff valve. Open the inlet (upstream) shutoff slowly until meter is full of water.
Open the outlet (downstream) valve slowly until air is out of meter and service line. Open a faucet slowly to allow entrapped air to escape. Close the faucet