Current position > Contact Us
Quick Answer: For corrosive chemical acid batching, select a flow meter with PTFE or PFA liner and Hastelloy C or tantalum electrodes. Electromagnetic flowmeters cover most acid batch lines from DN10 to DN300. Coriolis mass flowmeters are better for small batch accuracy below 100 kg/h. Silver Instruments supplies both types with 4-20 mA HART output.
Silver Automation Instruments has supplied acid batching meters to chemical plants in Vietnam, Indonesia, Thailand and Saudi Arabia. The common failure is not the flow sensor body. The failure is the liner and electrode material. A general purpose water meter fails because the rubber liner swells and the stainless steel electrodes pit. Batch accuracy drifts. The process adds too much acid or too little. The specification must start with chemical compatibility.
An electromagnetic flowmeter is the first choice for most acid batching lines. It has no moving parts and the pressure drop is low. Most acid solutions in batching have conductivity above 200 µS/cm. This is enough for a stable signal. The wetted liner must be PTFE or PFA. The electrodes must be Hastelloy C-276, tantalum or platinum. Silver Instruments AMF series electromagnetic flowmeters can be built with PTFE liner and Hastelloy C electrodes. The line size covers DN10 to DN300. Accuracy is plus or minus 0.5 percent of reading for flow velocity above 0.3 m/s. This works well for hydrochloric acid, sulfuric acid and sodium hydroxide.
For small batch dosing under 100 kg/h, a Coriolis mass flowmeter is a better fit. The SCF series from Silver Instruments measures mass directly. It handles DN3 to DN50 with plus or minus 0.2 percent accuracy. Use it for expensive additives, acid catalysts or exothermic mixing where mass ratio matters. A paint manufacturer in Vietnam replaced a positive displacement meter with an SCF Coriolis meter on a sulfuric acid catalyst line. The batch weight error dropped from 1.8 percent to less than 0.3 percent.
PTFE and PFA liners handle most acids at temperatures up to 120 Celsius. Electrode material selection depends on the acid type. Hastelloy C-276 works for hydrochloric acid and sulfuric acid in many concentrations. Tantalum is better for concentrated sulfuric acid at higher temperatures. Platinum works for nitric acid and mixed acids. Grounding rings should match the electrode material. If the pipe is non metallic, use grounding rings. Do not use 316L stainless steel electrodes in hydrochloric acid. They will pit and the meter will drift within weeks.
Install the meter on the discharge side of the batch pump. Keep the measuring tube full at all times. For vertical pipes, flow should move upward. This prevents air pockets and empty pipe errors. Air elimination is critical in acid batch dosing. One bubble in a 20 kg acid batch changes the final pH. In practice, most engineers skip this part. They focus on chemical compatibility but ignore air binding. The batch controller then overshoots and the product is off spec. Use an air release valve upstream if the acid line has frequent pump starts.
Most acid batch systems run at 2 to 6 bar and 25 to 80 Celsius. Silver Instruments meters are rated for 16 bar and 120 Celsius as standard. For ATEX Zone 1 or Zone 2 areas, order the meter with the required certification. Tell us the zone classification when you send the inquiry.
Use a screened cable for 4-20 mA HART signal. Keep the signal cable away from the pump variable frequency drive cable. Variable frequency drives are noisy in acid batching panels. A 4-20 mA HART signal plus a pulse output covers most batch controllers. If you need direct PLC integration, order the meter with RS485 Modbus RTU. Silver Instruments can configure the pulse width and the totalizer unit before shipment. This reduces field commissioning time.
In Vietnam, a fertilizer plant needed a nitric acid batch meter for a DN25 pipe. Flow range was 150 to 800 kg/h. Pressure was 4 bar. Temperature was 45 Celsius. We supplied an AMF electromagnetic flowmeter with PTFE liner and Hastelloy C electrodes. The plant reduced acid overfeed by 2.5 percent in the first month. In Indonesia, a chlor-alkali plant used an SCF Coriolis meter for 32 percent sodium hydroxide. The meter held plus or minus 0.2 percent mass flow accuracy for 14 months. In Thailand, a food ingredients factory uses Silver Instruments electromagnetic meters for citric acid and caustic CIP batches. The meters run 16 hours per day with no liner replacement after two years.
Send us the acid name and concentration. Include flow range in kg/h or m3/h, pipe size DN, pressure in bar and temperature in Celsius. Also tell us if the area is ATEX Zone 1 or Zone 2. We will return a quote with liner, electrode and grounding ring options. Contact us at Tel: +86-25-68650347, WhatsApp: +86-25-52155837 or WeChat: +86 15365082610.
For most hydrochloric acid batch lines, an electromagnetic flowmeter with PTFE liner and Hastelloy C electrodes is the best choice. For flow rates under 100 kg/h, use a Coriolis mass flowmeter.
Clamp-on ultrasonic flowmeters can handle acid batching for flow verification or large transfer lines. They are not the first choice for small batch accuracy below 1 percent. Pipe wall condition and acid concentration affect the signal.
PTFE and PFA liners are safe for sulfuric acid in most concentrations and temperatures up to 120 Celsius. For acid above 98 percent concentration, confirm temperature and flow velocity with our engineers.
Send the minimum and maximum dosing flow rate, pipe size DN, acid concentration and viscosity. For electromagnetic meters, keep minimum flow above 0.3 m/s. For Coriolis meters, we check pressure drop and mass flow accuracy.
Most batch controllers accept 4-20 mA analog plus pulse output. Silver Instruments meters can supply 4-20 mA HART, pulse and RS485 Modbus RTU. This covers common PLC and batch controller inputs.
For acid batching infrastructure, start with the acid name, concentration, pipe size DN, flow range, pressure and temperature. Send these details to Tel: +86-25-68650347, WhatsApp: +86-25-52155837 or WeChat: +86 15365082610. We will propose a flow meter model and liner material for your exact process.
