selection requirements for magnetic level gauges for 60% sulfuric acid

Regarding the user's selection requirements for magnetic level gauges for 60% sulfuric acid (H₂SO₄) and 65% nitric acid (HNO₃),

 based on the parameters provided by technical personnel and the user's original requirements, the analysis is as follows:

Core Differences and Compatibility Analysis

Valve Body and Flange Materials

User Requirement: PVDF (Polyvinylidene Fluoride), suitable for highly corrosive media (such as concentrated sulfuric acid and nitric acid).

Technical Personnel's Recommendation: PP (Polypropylene), with weaker corrosion resistance than PVDF, only suitable for dilute acids or 

weakly corrosive environments at room temperature.

Conclusion: PP material does not meet the requirements. 60% sulfuric acid and 65% nitric acid will corrode PP at 60℃. It needs to be 

replaced with PVDF or PTFE-lined stainless steel (such as 316L+PTFE).

Pressure and Temperature Compatibility

User Requirement: 4 bar (PN16), 60℃.

Technical Personnel's Recommendation: Pressure rating not specified, but PP material typically withstands pressure ≤1.6 bar 

(room temperature), and even lower pressure at 60℃.

Conclusion: PP material cannot withstand 4 bar pressure; PVDF (pressure resistance up to 10 bar) or higher-pressure-resistant 

PTFE-lined stainless steel should be selected.

Structure and Function Matching

User Requirements: Side-mounted, 700mm center distance, DN50 flange, drain/vent plug.

Technical Support Provided: Side-mounted, 700mm center distance, DN50 flange, but drain/vent plug not mentioned.

Conclusion: It needs to be confirmed whether the technical support solution includes a drain/vent plug; otherwise, additional 

design is required.

Recommended Solution

Material Upgrade

Valve Body and Flange: Use PVDF or PTFE-lined stainless steel (316L+PTFE) to ensure corrosion resistance and pressure resistance.

Float: Use PVDF-coated magnet or 316L stainless steel float to prevent corrosion-induced jamming.

Structural Optimization

Drain/Vent Plug: Install PVDF drain/vent valves at the bottom and top of the level gauge for easy maintenance.

Remote transmission function (optional): If remote monitoring is required, a 4-20mA transmitter or magnetic switch can be added,

 but it needs to be confirmed whether the user requires it.

Parameter Confirmation Sheet

Item User Requirements Technical Support Solution Recommended Solution

Media 60% H₂SO₄, 65% HNO₃ Same as above Same as above

Maximum Pressure 4 bar (PN16) Not specified PVDF or PTFE-lined stainless steel (PN16)

Maximum Temperature 60℃ Not specified Same as above

Valve Body/Flange Material PVDF PP PVDF or PTFE-lined stainless steel

Installation Method Side-mounted Side-mounted Same as above

Center Distance 700mm 700mm Same as above

Flange Type Overlap (PN16) Not specified Overlap (PN16, EN 1092-1)

Process Connection DN50 DN50 Same as above

Drain/Exhaust Plug Requirement Not mentioned Install PVDF drain/exhaust valve

Action Recommendation

Immediate Feedback: Inform the technical staff about the material mismatch issue and request a PVDF or PTFE-lined stainless steel solution.

Cost Comparison: PVDF level gauges are more expensive than PP level gauges, but PTFE-lined stainless steel may be more economical;

 the choice should be based on the budget.

Sample Testing: If the user has concerns about the material, samples can be provided for corrosion testing (e.g., immersion experiment).

Emergency Alternative: If delivery time is tight, PVDF level gauges can be used temporarily, but the user must be clearly informed of the 

risks associated with PP materials.

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