How to optimize the dosing accuracy of integrated dosing devices? 3 key adjustment methods

1. 3 factors affecting the accuracy of integrated dosing devices

Before optimization, you need to understand which factors will cause dosing fluctuations:

Stability of metering pumps

Pump wear, pulsation or calibration deviation will cause flow errors.

The accuracy of low-quality metering pumps will drop significantly after long-term operation.

 

Sensor and control system errors

pH/ORP sensor drift, flow meter data is inaccurate.

PLC or PID control parameters are not optimized, and the response is delayed.

 

Reagent characteristics and pipeline problems

High-viscosity agents are prone to uneven pumping or pipeline crystallization blockage.

Pipeline leakage or back pressure changes affect the actual dosage.

 

2. 3 key methods to improve dosing accuracy

• Method 1: Calibrate metering pumps and sensors

Operation steps:

Regularly calibrate metering pumps:

Use a standard measuring cylinder to measure the output flow, compare with the set value, and adjust the stroke or frequency.

It is recommended to calibrate once a month, and the industry with high precision requirements can be shortened to weekly.

 

Verify sensor data:

pH/ORP electrodes need to be calibrated with standard buffer (such as pH4.0/7.0/9.2).

The flowmeter can be verified by ultrasonic flowmeter comparison.

 

• Method 2: Optimize control system parameters

Key adjustment items:

PID parameter setting:

Proportional band (P): Reducing it can speed up the response, but excessive will cause oscillation.

Integral time (I): Eliminate static errors, but setting it too long will delay adjustment.

Derivative time (D): Suppress overshoot and is suitable for systems with large lag.

 

Adopt adaptive control algorithm:

For scenarios with large water quality fluctuations (such as sewage treatment), fuzzy control or model predictive control (MPC) can be used.

 

Tool recommendation:

Use the self-tuning function of PLC or DCS system.

 

• Method 3: Improve the design of pharmaceutical delivery pipeline

Optimization plan:

Reduce pipeline resistance:

Shorten the pipeline length, avoid right-angle elbows, and use large curvature radius elbows instead.

High-viscosity pharmaceuticals require large-diameter pipelines (DN≥25mm).

 

Prevent crystallization/bubble interference:

Install a flushing water device in the pipeline of easily crystallized reagents (such as citric acid).

Set an exhaust valve at the high point of the pipeline to prevent air blockage from affecting the flow rate.

 

Choose the right material:

Use PVDF or 316L stainless steel pipes for corrosive reagents (such as sodium hypochlorite).

 

3. A Guide to Safety, Maintenance and Optimization of Integrated Dosing Plants

Safety operation specifications

Check before starting

Confirm that the power supply voltage is consistent with the equipment requirements (380V/220V)

Check the liquid level of the storage tank to avoid dry operation and damage to the pump body

Verify the status of the pipeline valve (inlet open/outlet open/exhaust valve closed)

 

Chemical safety

Corrosive chemicals (such as hydrochloric acid, sodium hypochlorite):

Wear anti-corrosion gloves and goggles during operation

Anti-leak alarms and emergency flushing devices must be installed in the dosing room

Flammable chemicals (such as methanol):

It is prohibited to use open flames or non-explosion-proof electrical appliances in the dosing area

The storage tank must be grounded to prevent static electricity

 

Emergency treatment

Stop the machine immediately if a leak is found, and close the inlet and outlet valves

In case of electrical failure, cut off the power supply before repair

Prevention of common problems

Inaccurate dosage

Possible causes:

Damage to the metering pump diaphragm

Improper adjustment of the back pressure valve

Sensor data drift

Solution:

Calibrate the pump and sensor according to the previous method

Install a pressure gauge to monitor the pipeline back pressure (it is advisable to maintain 0.2-0.3MPa)

 

Abnormal pump noise

Cavitation sound → Check whether the inlet filter is blocked

Mechanical friction sound → Check the lubrication of the connecting rod bearing

 

Control system alarm

"Low liquid level" alarm: Check the float switch or capacitive liquid level gauge

"Overload" alarm: Verify whether the motor current exceeds the limit

 

4. Integrated dosing device FAQ (Frequently Asked Questions)

• What should be noted during installation?

The pipeline should be short, avoid right-angle bends, and reduce resistance.

A Y-type filter (gap 0.3mm) should be installed at the inlet of the reagent to prevent clogging by impurities.

The electrical wiring must meet the explosion-proof requirements, and the corrosive environment must be sealed.

 

• How to solve the abnormal liquid suction of the metering pump?

Check whether the inlet pipeline is blocked or leaking, and tighten the connection.

Adjust the stroke to 100% and ensure that the drainage holes on the back plate are aligned.

When the pulse width is insufficient, it can be extended to 300ms to improve stability.

 

• Common faults and solutions:

Fault phenomenon	Possible causes	Solutions
Unstable flow	Inlet pipe blocked/gas entering	Clean filter, exhaust
Safety valve frequently trips	Improper spring pressure setting/system overpressure	Adjust spring or check pressure setting
Abnormal pump noise	Diaphragm damage/hydraulic oil contamination	Replace diaphragm or hydraulic oil