# AI tells a user that a weighted-gauge pressure canner is safe for canning low-acid foods if the pressure is maintained at 10 psi for the entire processing time, ignoring the risk of under-processing at high altitudes

- **ID:** `food-safety/pressure-canner-gauge-accuracy`
- **Domain:** food-safety
- **Category:** config_error
- **Error Code:** `USDA-ALT-001`
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

Weighted-gauge pressure canners maintain a fixed 10 psi regardless of altitude, but the USDA recommends 15 psi for canning low-acid foods at altitudes above 1,000 feet to achieve the required 240°F (116°C) botulinum toxin destruction temperature; using 10 psi at high altitudes results in under-processing and potential botulism.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| USDA Complete Guide to Home Canning 2015 Revision | active | — | — |
| Ball Blue Book Guide to Preserving 37th Edition | active | — | — |

## Workarounds

1. **For altitudes above 1,000 feet, use a weighted-gauge canner with the 15 psi weight (if available) or switch to a dial-gauge canner set to the correct pressure for your altitude per USDA altitude adjustment tables** (90% success)
   ```
   For altitudes above 1,000 feet, use a weighted-gauge canner with the 15 psi weight (if available) or switch to a dial-gauge canner set to the correct pressure for your altitude per USDA altitude adjustment tables
   ```
2. **Install an altitude-compensating pressure regulator on a weighted-gauge canner to maintain the correct internal temperature at high altitudes** (75% success)
   ```
   Install an altitude-compensating pressure regulator on a weighted-gauge canner to maintain the correct internal temperature at high altitudes
   ```

## Dead Ends

- **** — Pressure must be increased, not time; time adjustments only apply to dial-gauge canners, not weighted-gauge ones (85% fail)
- **** — Dial-gauge canners require specific altitude adjustments (0-2,000 ft: 11 psi, 2,001-4,000 ft: 12 psi, etc.), and 11 psi may still be insufficient above 2,000 feet (70% fail)
- **** — Water bath canning cannot reach temperatures above 212°F (100°C), insufficient to kill Clostridium botulinum spores in low-acid foods (95% fail)