Gas metering devices
- SG-1, AGBM-1.6
- Gallus 2000 G1,6, G2,5, G4
- NPM-G1,6, NPM-G2,5, NPM-G4
- BK-G1,6, BK-G2,5, BK-G4
- SGK-1.6, SGK-2.5, SGK-4
- SGK-1.6, SGK-2.5, SGK-4 (T) *
- Helios G1.6 Helios G2.5 Helios G4
- SGB-G2,5, SGB-G4-1
- SGB-G2,5 Signal, SGB-G4 Signal
- SGM-2 G4, SGMN-1 G6, SGMN-1M (1)
- Metrix G6
- BK-G6 (T), BK-G10 (T), BK-G16 (T), BK-G25 (T)
- UBSG-001 G6, UBSG-001 G10, AGAT-G16, AGAT-G25
- Metrix G10
- RGA, RGA-Ex, G10, G16
- G10, G16, G25, G40
- Metrix G16, Metrix G25
- VK-G40, VK-G65
- Metrix G40, Metrix G65
- RVG G16-G250
- Delta G16-G650
- RSG "Signal"
- TZ / Fluxi G65-G6500
- TRZ (G65-G4000)
- STG 100-1600
- SG-16 (MT) 100-4000
- Turbo Flow GFG-ΔP Series
- Turbo Flow GFG-F Series
- Turbo Flow TFG Series
- PURG-100, PURG-200, PURG-400
- PURG-800 (-EK), PURG-1000 (-EK), PURG-1600 (-EK), PURG-2500 (-EK)
Diaphragm counter (diaphragm, chamber) is a gas meter, the principle of which is based on the fact that with the help of various moving conversion elements, the gas is divided into fractions of a volume, and then they are cyclically summed.
The diaphragm counter (fig. 8.10 ) consists of body 1, cover 2, measuring mechanism 3, crank-lever mechanism 4, which connects the moving parts of the diaphragms (diaphragms) with the upper valves 5 of the gas distribution device, valve seats (lower part of the switchgear) and the counting mechanism . The body and cover of the meter can be:
- - steel, stamped with a coating against corrosion and sparking. The connection of the steel stamped body and the cover is carried out by means of a sealing material and a clamping strip 6 (see. Fig. 8.10 ), which ensure a tight fit of the two parts to each other;
- - aluminum, cast. The aluminum case and cover of the meter are sealed with special gaskets and a set of screws, one of the screws is made with a seal.
Details and components of the measuring mechanism for membrane meters are made of plastic. The use of plastic measuring mechanisms significantly reduces the cost of production, increases resistance to the effects of chemical components in gases, significantly reduces the coefficient of friction in the moving parts of the meter.
Depending on the design and volume of the measured gas, the measuring mechanism may consist of two or four chambers. A schematic diagram of the diaphragm counter operation is shown in fig. 8.11 .
|Camera position counter||Camera 1||Camera 2||Camera 3||Camera 4|
The meter works as follows:
a) the measured gas flow through the inlet pipe enters the upper cavity of the housing and then through the open valve into chamber 2. Increasing the gas volume in chamber 2 causes the diaphragm to move and the gas is expelled from chamber 1 to exit from the valve seat and further to the meter outlet. After approaching the lever of the diaphragm to the wall of the chamber 1, the diaphragm stops as a result of switching valve groups. The movable part of the valve chambers 1 and 2 completely overlaps the valve seats of these chambers, disabling this chamber unit.
b) The valve of chambers 3 and 4 opens the gas inlet from the upper cavity of the meter body into chamber 3, fills it, which causes the diaphragm to move and gas is expelled from chamber 4 to the outlet through the slots in the valve seat. After approaching the lever of the diaphragm to the wall of the chamber 4, the diaphragm stops as a result of turning off the valve block of the chambers 3, 4.
c) The valve of chambers 1, 2 opens the gas inlet from the upper cavity of the meter case into chamber 1. When gas is supplied into chamber 1, diaphragm 1, 2 moves, displacing gas from chamber 2 into the outlet through the slots in the valve seat. After approaching the lever of the diaphragm to the wall of the chamber 2, the diaphragm stops as a result of turning off the valve block of the chambers 1, 2.
d) The valve of the chambers 3, 4 opens the gas inlet from the upper cavity of the meter case into chamber 4. When gas is supplied to chamber 4, diaphragm 3, 4 moves and forces gas out of chamber 3 to the outlet through slots in the valve seat. After approaching the lever of the diaphragm to the wall of the chamber 3, the diaphragm stops as a result of turning off the valve block 3, 4.
The process is repeated periodically. The counting mechanism counts the number of moves of the diaphragms (or the number of cycles of operation of the measuring mechanism n). For each cycle, the gas volume Vc is displaced, equal to the sum of the volumes of chambers 1, 2, 3, 4. One complete revolution of the output axis of the measuring mechanism corresponds to 16 cycles.
It is necessary to remove the meter from the gas pipeline (not everyone will be able to restore the seals on the cap nuts) !!!!!!
The essence of the methods to the insult is simple - inside the outlet nozzle it is necessary to break the tightness of the connection of the plastic insert and the meter case. I just peeled back the plastic slightly inside with a screwdriver and tampered with the sealing rubber ring with tweezers and removed its result, exceeded all expectations, the meter twists in half.
As far as I understand, counters of this type are very sensitive to the pressure drop of the gas input-output after this procedure, you can stick a part of the seal into place, otherwise, when I turn on the gas stove, it didn’t twist the poor guy at all ....
Started counting only when the gas boiler is on. Well that's all. After that we put the counter on a regular place and restore the seals.
In a turbine gas meter (Fig. 8.13 ), under the influence of gas flow, the turbine wheel is rotated, the speed of which is directly proportional to the flowing volume of gas. The turbine speed is transmitted through a reduction gearbox and a gas-tight magnetic coupling to a counting mechanism located outside the gas cavity, showing (incrementally) the total volume of gas under operating conditions that has passed through the device.
1, 10 - measured cross section; 2 - the inclusion of pressure; 3 - magnetic coupling; 4 - counting mechanism; 5 - thermo probe RT-100; 6 - control thermometer; 7 - output channel; 8 - pulse sensors; 9 - turbine wheel; 11 - the displacing body.
A permanent magnet is fixed on the last gear of the gearbox, and near the wheel there are two reed switches, the frequency of contact closure of the first one is proportional to the speed of rotation of the turbine rotor, i.e. the gas flow rate. When a powerful external magnetic field appears, the contacts of the second reed switch are closed, which is used to signal unauthorized interference.
Structurally, turbine meters manufactured in Russia are a pipe section with flanges, in the flow part of which the inlet flow straightener, the turbine assembly with the shaft and rotational bearing bearings and the rear bearing are located in a downstream direction. A plunger oil pump assembly is installed on the meter case, with which liquid oil is delivered to the bearing area through pipes. The turbine casing provides places for the installation of sensors of the apparatus (for measuring pressure, temperature, pulses).
According to the degree of automation of the measurement process and the processing of measurement results, turbine meters are available in the following configuration options:
- - for separate measurements of variables of monitored parameters with arbitrarily selected means of processing measurement results (manual counting devices, microcalculators, etc.);
- - for semi-automatic measurements of variables of monitored parameters with computing devices for processing measurement results and devices with manual entry of values of conditionally constant parameters or manual correction of measurement results and calculations;
- - for automatic measurements of all monitored parameters with computing devices for processing measurement results.
In connection with the increase in the types of equipment, the need arose for measuring instruments that would have a relatively large carrying capacity and a large measurement range with relatively small overall dimensions. These conditions are satisfied with rotary gas meters, which additionally have the following advantages: no need for electricity, durability, ability to monitor the workability of the pressure drop work on the meter during its operation, insensitivity to short-term overloads. Rotary counters are widely used in public utilities, especially in heating boilers, as well as in small and medium-sized enterprises.
Rotary (rotary) meter - chamber gas meter, in which eight-shaped rotors are used as a converter element.
Fig. 8.12 Rotary gas meter type RG
11 - the case; 2 - the rotor.
The rotary gas meter of the RG type consists of the case 1, inside of which two identical eight-shaped rotors 2 of the transmission and counting mechanisms, connected with one of the rotors, rotate. The rotors are driven into rotation under the action of the pressure difference of the gas flowing through the upper inlet and outgoing through the lower outlet. During rotation, the rotors run in their side surfaces. Synchronization of rotor rotation is achieved by using two pairs of identical gear wheels mounted on both ends of the rotors in the end boxes outside the measuring chamber-body. To reduce friction and wear, the rotor gears are constantly lubricated with oil poured into end boxes.
The volume of gas displaced by a half-turn of one rotor is equal to the volume bounded by the inner surface of the housing and the lateral surface of the rotor in a vertical position. Four such volumes are displaced for a complete rotation of the rotors.
In the manufacture of rotary meters, special attention is paid to the ease of rotation of the rotors and the reduction of unrecorded gas leaks through the meter. The ease of travel, which is a qualitative indicator of low friction in the mechanism and, consequently, low pressure loss in the meter, is ensured by installing rotor shafts on ball bearings, minimizing friction in the gearbox and counting mechanism, as well as a rational choice of the design dimensions and rotor speed. Reducing gas leaks is achieved by careful processing and mutual adjustment of the inner surface of the housing and the friction surfaces of the rotors. The gap between the casing and the rectangular pads located at the ends of the largest diameters of the rotors varies from 0.04 to 0.1 mm, depending on the type of meter. In the manufacture of meters, special attention is paid to static balancing and rotor processing.
Vortex flowmeters are called, based on the dependence on the flow rate of the pressure oscillations that occur in the flow in the process of vortex formation or oscillation of the jet, or after an obstacle of a certain shape that is installed in the pipeline, or a special swirling flow.
The name of the vortex flowmeters received from the phenomenon of disruption of the vortices that occur when an obstruction is obstructed by a stream of liquid or gas, usually in the form of a truncated trapezoidal prism (Fig. 8.9 ). Behind the body of the flow is a sensing element that perceives vortex oscillations.
The advantages of vortex flow meters include: no moving parts, pressure and temperature independence of readings, large measurement range, output frequency measurement signal, possibility of obtaining universal calibration, relatively low cost, etc.
The disadvantages of vortex flowmeters include significant pressure losses (up to 30–50 kPa), limitations on their applicability: they are not suitable at low flow rates of the medium, to measure the flow of polluted and corrosive media.
Acoustic are flow meters based on the measurement of an effect that occurs when oscillations pass through a stream of liquid or gas and are dependent on flow. Almost all acoustic flowmeters used in practice work in the ultrasonic frequency range and are therefore called ultrasonic.
Most industrial ultrasonic flowmeters use effects based on the movement of acoustic oscillations of a moving medium. They serve to measure the volumetric flow rate, because the effects that occur when acoustic oscillations pass through the flow of a medium (liquid or gas) are related to the velocity of the medium. In fig. 8.8 shows the primary transducers of ultrasonic flow meters.
To enter acoustic oscillations into the stream and to receive them at the outlet of the stream, emitters and oscillators are necessary — the main elements of the primary transducers of ultrasonic flow meters. When compressing and stretching in certain directions of some crystals (piezoelements), electric charges form on their surface, and vice versa, if a potential difference is applied to these surfaces, the piezoelectric element will stretch or shrink depending on which of the surfaces has more voltage, the reverse piezo effect. These effects are based on the method of converting a variable electric potential difference on the crystal faces into acoustic (mechanical) oscillations of the same frequency (for emission radiation) or vice versa - converting acoustic oscillations into a variable electric potential difference on the crystal faces (for the oscillation receiver).
The advantages of ultrasonic flow meters are a wide range of flow measurement and the possibility of using microprocessor technology. The main disadvantage of ultrasonic flow meters is sensitivity to the content of solid and gaseous inclusions.