In the selection of flow control equipment，the measurement accuracy of the HQLDG electromagnetic flowmeter directly affects process efficiency。This article provides an in-depth analysis of 3 key indicators：medium electrical conductivity，flow velocity range and installation method，helping you select accurately from series such as HQLDE-C and HQLDJ。As a high-tech enterprise focusing on sensor R&D for 15 years，Shenghongchuang Instruments will guide you in mastering the core technical points of electromagnetic flowmeters。

I、Analysis of Core Technical Indicators of Electromagnetic Flowmeters

The measurement accuracy of electromagnetic flowmeters is affected by multiple factors，among which medium electrical conductivity is the most critical technical parameter。According to the ISO 6817 standard，the HQLDG series requires the measured liquid to have an electrical conductivity of ≥5μS/cm，while special models such as HQLDE-C can support low-conductivity media of 1μS/cm。In actual selection，please note：strongly corrosive media in the chemical industry should be paired with PTFE lining，while the sanitary HQLDJ series is recommended for the food and pharmaceutical fields。Through a patented electrode structure design（Patent No. ZL2020XXXXXX.X），Shenghongchuang Instruments enables the HQLDW electromagnetic flowmeter to maintain a measurement accuracy of ±0.5% even in media containing solid particles。

II、Selection Comparison Table for Different Operating Conditions

III、Impact of Installation Method on Accuracy

The installation position of an electromagnetic flowmeter directly affects measurement stability。According to the requirements of GB/T 18659-2018，the HQLDC electromagnetic flowmeter requires a straight pipe section of 10 times the pipe diameter upstream and 5 times the pipe diameter downstream。Common misconceptions include：installing the sensor within 3 meters of the pump outlet may cause reading fluctuations，and when the HQLDE-DC model is installed vertically，a full-pipe state must be ensured。Through CFD fluid simulation，the Shenghongchuang technical team found that when the LDD electromagnetic flowmeter is installed at a 45° inclination，it delivers the best measurement performance for media containing bubbles。

IV、In-depth Analysis of Industry Application Scenarios

In the field of municipal wastewater treatment，the LDW electromagnetic flowmeter，with its IP68 protection rating and 0.2% long-term stability，has become the preferred choice for aeration tank flow monitoring。In an upgrade and renovation project for a provincial-level wastewater treatment plant，after replacing imported brands with Shenghongchuang LDC electromagnetic flowmeters，annual maintenance costs were reduced by 37%。The chemical industry pays more attention to explosion-proof performance，and the HQLDG-Ex series has passed NEPSI certification（No. CNEx18.XXXX），enabling stable operation in Zone1 hazardous areas。

V、Frequently Asked Questions on Technical Evaluation

Q：How can an electromagnetic flowmeter ensure accuracy under low-flow-velocity operating conditions？
A：The HQLDE-DC electromagnetic flowmeter adopts multi-electrode array technology，and can still achieve Class 1.0 accuracy at a flow velocity of 0.05m/s。Its principle is to improve the signal-to-noise ratio by increasing the number of electrode pairs（4 pairs for the standard model，8 pairs for the high-precision model）。

Q：How should models be selected in environments with strong electromagnetic interference？
A：It is recommended to select the HQLDJ-Z model with double shielding，which adopts an aerospace-grade coaxial cable design。Actual testing shows an error of ≤0.3% under 10kV/m field-strength interference。

VI、Why Choose Shenghongchuang Instruments

As a high-tech enterprise receiving key support in a national-level new area，we have：1）an electromagnetic flowmeter calibration laboratory（CNAS LXXXX certification）；2）15 years of industry service experience，with more than 3000+ projects delivered in total；3）a 7×24-hour technical response system。We are now offering first-time purchasing customers a free operating-condition analysis service。Click the online consultation on the official website to obtain a dedicated selection solution for the HQLDG electromagnetic flowmeter。