Nitric Acid HNO₃ Magnetic Level Gauge Selection

Regarding the user's selection requirements for magnetic level gauges for 60% sulfuric acid (H₂SO₄) and 65% nitric acid (HNO₃), a key material mismatch was identified based on the parameters provided by technical personnel and the user's original requirements. The following is a detailed analysis and solution:

 

I. Core Issue: Material Mismatch

User Requirements:

Valve Body/Flange Material: PVDF (Polyvinylidene Fluoride), specifically designed for highly corrosive media (such as concentrated sulfuric acid and nitric acid), exhibiting excellent chemical corrosion resistance, particularly suitable for 60% sulfuric acid and 65% nitric acid at 60℃.

 

Pressure Rating: PN16 (4 bar), requiring material to meet both pressure resistance and corrosion resistance requirements.

 

Technical Personnel Solution:

Valve Body/Flange Material: PP (Polypropylene), with significantly weaker corrosion resistance than PVDF.

 

PP Applicable Scenarios: Dilute acids (such as ≤30% sulfuric acid), mildly corrosive environments at room temperature.

 

PP Risks: 60% sulfuric acid at 60℃ will accelerate the corrosion of PP, leading to leakage or equipment damage; PP may deform under 4 bar pressure, making long-term stable operation impossible.

 

II. Solution: Material Upgrade and Parameter Confirmation

 

Material Replacement Recommendations

**PVDF Preferred:**

**Advantages:** Resistant to corrosion from 60% sulfuric acid and 65% nitric acid; temperature resistance ≥80℃; pressure resistance up to 10 bar, fully covering user operating conditions.

 

Application Case: Level measurement of highly corrosive media in the chemical and electroplating industries.

 

Alternative Solutions (if budget is limited):

* **PTFE-lined stainless steel (316L+PTFE):** Lined with PTFE, with an outer layer of pressure-bearing stainless steel. Cost is lower than full PVDF, but the reliability of the lining process needs to be confirmed.

* **ETFE (ethylene-tetrafluoroethylene copolymer):** Corrosion resistance is close to PVDF, cost is slightly lower, but market application is less common.

 

**Key Parameter Confirmation:**

* **Drain/Air Plug:** It needs to be clarified whether the technical personnel's solution includes this. If not, a PVDF valve needs to be installed.

* **Float Material:** It is recommended to use PVDF-wrapped magnets or 316L stainless steel floats to avoid corrosion-induced jamming.

* **Flange Standard:** Confirm whether it is an lap joint type (EN 1092-1 PN16) to match the user's process piping. III. Recommended Configuration Table

 

Item | User Requirements | Technical Personnel Solution | Recommended Solution

 

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

 

Maximum Pressure | 4 bar (PN16) | Pressure rating 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, EN 1092-1) | 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

 

IV. Action Recommendations

Immediately provide feedback to technical personnel: Clearly state that PP material is unsuitable and request a PVDF or PTFE-lined stainless steel solution. Cost and Delivery Communication: PVDF level gauges are typically 30%-50% more expensive than PP gauges, but offer greater long-term reliability. If the user accepts the alternative, the lining process and delivery time must be confirmed.

 

Sample Testing (Optional): Providing PVDF material samples for corrosion testing (e.g., immersion experiments) enhances user confidence.

 

Emergency Alternative: If the user insists on using the existing solution, a risk disclosure statement must be signed, clearly outlining the corrosion risk of PP material at 60% sulfuric acid/60℃ and the potential consequences.

 

V. Summary: The current solution requires adjustment due to material incompatibility (PP cannot withstand 60% sulfuric acid/nitric acid and 4 bar pressure). We recommend using a PVDF magnetic level gauge with a supplementary drain/vent plug design to ensure long-term stable operation under strong corrosion and high pressure conditions. For further technical support or quotations, please contact:

CIXIFM Winny

Email: sales01@cxflowmeter.com

WhatsApp: +86 18049841995