Location -> News
News
Hydraulic Diaphragm Metering Pump for Nitric Acid Solution
Hydraulic Diaphragm Metering Pump for Nitric Acid Solution
Based on the customer's request for a hydraulic diaphragm pump, considering the highly corrosive nature of nitric acid solution and the required process parameters, the following optimization solution is recommended:
I. Core Parameter Compatibility Analysis
Flow and Pressure
The recommended model YDJCM-300/1.7, with a rated flow of 300 L/h and a pressure of 1.7 MPa, fully meets the requirements, but the safety valve redundancy design needs to be verified.
Risk Point: The built-in safety valve has a cracking pressure of 2.3 MPa (1.35 times the rated pressure). While this meets some industry standards, the API 675 standard recommends a cracking pressure of ≤1.25 times the rated pressure (i.e., ≤2.125 MPa).
Optimization Suggestion: Add a secondary safety valve (cracking pressure 2.0 MPa) to provide dual protection and prevent overpressure caused by main valve failure.
Wetted Material
The original wetted material required was 304L, but the recommended pump body wetted material is 316L.
Advantages: 316L stainless steel has a chromium (Cr) content of ≥16%, a nickel (Ni) content of ≥10%, and a molybdenum (Mo) content of 2%-3%. Its resistance to nitric acid corrosion is significantly superior to 304L (304L is only suitable for nitric acid with a concentration of ≤65%).
Risk: Seals (such as diaphragms and O-rings) made of rubber (such as EPDM) can be corroded by nitric acid, leading to leakage.
Optimization Suggestions:
Diaphragms: Choose PTFE (polytetrafluoroethylene), which offers excellent nitric acid corrosion resistance (corrosion rate <0.001 mm/year).
Seals: Replace with FFKM (perfluoroelastomer) or PTFE-coated rubber to prevent nitric acid penetration.
II. Accuracy and Control Solution
Open-Loop Control Accuracy
The open-loop control accuracy of a hydraulic diaphragm pump is typically ±1.5%, but the requirement is >1%, requiring closed-loop control.
Optimization Solution:
Add an electromagnetic flowmeter (made of nitric acid-resistant PTFE) to output a 4-20 mA signal to a frequency converter (such as the Schneider ATV630 series).
Frequency Converter Parameter Settings: PID adjustment cycle ≤ 0.1 second, response frequency ≥ 50 Hz, ensuring flow fluctuation ≤ ±0.5%.
Integrate a density-flow correction algorithm in the DCS system (adjust the frequency converter output in real time based on the nitric acid concentration-temperature-density curve).
Frequency Converter Motor Compatibility
A 1.1 kW-4-rated standard frequency converter motor (380V) can meet flow regulation requirements, but the motor torque must be verified to match the pump's load characteristics (especially during startup and low-speed operation).
Recommendation: Use a dedicated frequency converter motor (such as the Siemens 1LE0001 series), which offers constant torque output to avoid the torque shortage of standard motors at low frequencies.
III. Operation and Maintenance Risks and Optimization Suggestions
Diaphragm Life Monitoring
74% nitric acid accelerates diaphragm aging (PTFE diaphragms have a lifespan of approximately 8,000 hours). Nitric acid leakage from a rupture could potentially cause a safety incident.
Optimization Solution:
Use a double diaphragm structure (such as the German Altech FKM series), with glycerin filling the gap between the inner and outer diaphragms as the monitoring medium. Install a diaphragm rupture sensor (pressure switch or level switch) to trigger an alarm and shut down the machine in the event of a leak.
Hydraulic Oil Management
A diaphragm rupture can cause nitric acid to seep into the hydraulic oil chamber, where it will emulsify and lose its lubricating properties, accelerating pump head wear.
Optimization Solution:
Use ISO VG32 anti-wear hydraulic oil (with anti-corrosion additives) and replace it every three months.
Install a hydraulic oil acid value tester (such as the Koehler K83100 from the US). Replace the oil immediately if the acid value exceeds 0.5 mgKOH/g.
For further pricing or technical details on specific models, please contact CIXIFM Winny at sales01@cxflowmeter.com or WhatsApp at +86 18049841995.
Last：沒有了 Next：fire water pump
