How to select the boiler hot water flow meter
Time: 2024-07-03
Correct selection for the application of boiler hot water flowmeter is critical, first of all, must be based on the parameters of the measured fluid to select the appropriate caliber, lining and electrode material, and secondly, according to the user's requirements for the boiler hot water flowmeter to select the instrument enclosure level of protection and output function.
![[!--tupainalt1--]](/d/file/p/2024/07-03/00c24059c065825f7721314ce75929fe.jpg)

Project Overview
According to relevant data, the meter in actual use in 2/3 of the failure is caused by the wrong selection, need to pay special attention to.
The selection process generally consists of the following parts:
- (1)Collect the parameters of the measured fluid fluid name, maximum / minimum flow rate, maximum pressure, maximum / minimum temperature, fluid conductivity, fluid abrasive and corrosive to the instrument, whether there is a backflow (reverse flow) occurs, whether there is a negative pressure in the pipe, and so on.
- (2)Flow rate and caliber and measurement accuracy of the relationship between the measurement accuracy of boiler hot water flowmeter caliber and flow rate related to the flow rate of large precision will be high, and vice versa, the smaller the flow rate of the lower precision is lower, generally measurable minimum flow rate of 0.1m/s (i.e., the flow rate can ensure the accuracy of the measurement). Can be based on the flow range in the table to choose the appropriate flow meter caliber: measurement of clean water, the economic flow rate is 1.5 ~ 3m / s, at this time the pipe loss is small, the pump consumes low power; measurement of easy to crystallize scaling of the liquid, the appropriate increase in the flow rate to > 3m / s is appropriate, the flow rate of the high to play a role in the self-sweeping, thereby preventing the liquid from adhering to the pipe wall and the electrode; measurement of the wear and tear of the slurry and other fluids should be appropriately reduce the flow rate, in < 2m / s is appropriate to reduce the medium on the lining and electrode wear; practical application of pipeline fluid flow rate higher than 7m / s less, more than 10m / s is more rare.
- (3)Electrode material selection boiler hot water flowmeter in which only the electrode is in contact with the measured medium, plays the role of transferring the induced voltage. Qualified electrode materials are not allowed to produce corrosion, nor electrode surface effect.1. HB is not resistant to corrosion of nitric acid, for concentrations greater than 10% of hydrochloric acid and aluminum sulfate will produce electrode surface effect, so that the flowmeter output is unstable.2. Tantalum will not be corroded by the water, but in contact with the water is easy to be oxidized, resulting in an electrode surface effect to generate an insulating layer, so that the flowmeter output is unstable.3. Platinum electrodes on hydrochloric acid have Good corrosion resistance, but when measuring hydrochloric acid with a concentration greater than 10%, the flowmeter output fluctuations will be large. Platinum electrode for measuring low pressure, hydrogen peroxide, due to the electrode surface effect will produce aerosol, impede the electrical pathway, so that the flowmeter output is not stable.
- (4)The choice of lining material is based on the corrosiveness, abrasiveness and temperature of the measured medium.