1, the vortex street flowmeter
, turning on the power supply valve does not open, a signal output.
Solution: (1) sensors (
Or detecting element)
The output signal of the block or bad earth, the external electromagnetic interference;
(2) meter too close to or high frequency and high voltage devices, space electromagnetic radiation interference, affect the instrument;
(3) installation pipeline has the strong vibration;
(4) converter of high sensitivity, high sensitive to interference signal;
The measures should be taken is to strengthen the shielding and grounding, eliminate the pipeline vibration, adjustment to reduce the sensitivity of converter.
2, in intermittent vortex flowmeter, the working state of power supply is not broken, the valve closed, the output signal is not back to zero;
Perhaps the main cause is pipe oscillation effect and external electromagnetic interference.
Solution: take down converter, the sensitivity of the improve the trigger level of shaping circuit, can suppress noise and overcome during intermittent triggered by mistake.
3, current state, the downstream shutoff valve, the output is not back to zero, upstream of the valve output back to zero, this mainly comes from upstream fluid pulsation pressure flowmeters.
If the vortex flow meter installed in a tee branch pipe, and the upstream head pressure pulsation, or upstream of vortex flowmeter is the power source of the pulse (
Such as piston pump or roots blower)
, the fluctuating pressure cause false signals of vortex street flowmeter.
Solution: the downstream valve installed to the upstream of vortex flowmeters, close the upstream of the valve during downtime, and isolate the impact of fluctuating pressure.
But when installation, upstream of the valve should be far away from the vortex flowmeter, and ensure the enough length of straight pipe.
4, current status, upstream of the valve output not back to zero, only the downstream valve output back to zero, this fault is caused tube fluid disturbance, disturbance from vortex flow meter downstream piping.
If vortex flowmeter downstream straight pipe in pipe network is shorter and the exit of pipe networks and other pipeline valves close distance, is the pipeline fluid disturbance (
Such as other downstream of the pipeline, valve, regulating valve frequent action)
Detecting element to the vortex street flowmeter, cause false signals.
Solution: extended downstream straight pipe section, reduce the influence of the fluid disturbance.
After 5, electricity, general flow, vortex street flowmeter output (
Signal does not change with flow, due to poor signal shield grounding or pick up location choice not appropriate, the electromagnetic interference is very serious,
For example, 50 hz frequency interference)
, completely inhibited the weak vortex signal, the output signal completely submerged by noise, then adjust the gain of valve opening, instrument, to no avail.
Detecting element connected to the converter between bolt, open the preamplifier input end, or detecting element has a signal wire and ground short cause the preamplifier input serious imbalance, common-mode interference with people, vortex signal noise suppression, output was completely interference control.
Pre-amplifier gain is too high, self-excited oscillation phenomenon, the output is locked on the self excitation frequency.
Solution: belong to electrical reasons caused as a result of the above, only strengthen the shielding and grounding, the reasonable line, reduce or eliminate interference, the normal work of the instrument to recover.
6, pipe (
Or the environment)
Strong vibration when the vibration direction and the direction of sensitive instrument detecting element, fully suppress the vortex vibration signal, the output signal is the vibration frequency signal.
Adjust the valve opening also can't change the output.
Solution: USES vibration reduction measures,
Add piping vibration, a fixed pipe)
, make clear direction of vibration, the vortex street flowmeter sensors around the pipe axis rotation and 90 ℃, the detecting element is sensitive to adjust to direction and perpendicular to the direction of vibration can reduce the influence of vibration mouth or decrease the gain of preamplifier and triggering sensitivity.
The above measures can eliminate vibration effect.
7 and flow pulsation of vortex signal & other;
Lock & throughout;
Without taking effective inhibition of pulsating flow influence, under the condition of pulsating flow separation on the vortex stability damage cannot be underestimated, if the pulse frequency in tune with the vortex signal frequency, may signal the vortex street & other;
Lock & throughout;
When the regulating valve, and near the frequency meter sensitivity, the output signal frequency will not change.
Solution: when the instrument installation of pipeline design, construction to absorb or measures to reduce fluid pulsation.
8, instrument more than verification period, instrument coefficient K changed;
Set the parameters of the (
The measuring tube diameter, for example, standard state density and instrument coefficient)
Analog conversion circuit of zero drift or range adjustment is wrong;
Power supply over the earth from ratings or ripple is too big.
Solution: put the instrument were quickly, timely check the parameters setting, regular calibration instrument zero and span, maintain integrity rate of the instrument.
9 container, vortex street flowmeter preach whistlers: (check exception
The flow rate is too high, cause body or detecting element,
Cavitation occurred in pipeline;
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