Heat Seal Tester Models: Compare STH-3, STH-3A, and STH-5
All three KHT STH heat seal testers comply with ASTM F88 and F2029. The right model depends on your testing volume, temperature gradient needs, record-keeping requirements, and budget. Side-by-side comparison below.
Entry-LevelSTH-3
Manual Heat Seal Tester
Single-point manual heat sealer for small labs and R&D. RT+10 to 250°C, ±1°C accuracy, ASTM F88/F2029 compliant. Ideal for routine QC on a known production recipe.
Temp Range
RT+10 ~ 250°C
Pressure
0.1–0.7 MPa
Accuracy
±1°C
Positions
1 (single)
Highest AccuracySTH-3A
Touchscreen Heat Seal Tester with Automatic Pressure
Touchscreen operation, automatic sealing pressure, and a built-in printer for test records. ±0.5°C accuracy — the tightest in the STH line — for documented routine QC on a single 300 × 10 mm jaw.
Temp Range
RT+10 ~ 250°C
Pressure
Automatic
Accuracy
±0.5°C
Positions
1 (single)
GradientSTH-5
5-Point Gradient Heat Seal Tester
Five jaws at five independent temperatures map your full seal curve in one run. Digital display, gradient testing per ASTM F2029. The workhorse for film qualification and SIT mapping.
Temp Range
RT+10 ~ 250°C
Pressure
0.1–0.7 MPa
Accuracy
±1°C
Positions
5 (gradient)
Model Comparison
STH-3 vs STH-3A vs STH-5: Choose Your Model
All three models comply with ASTM F88 and F2029. The right choice depends on your testing volume, gradient needs, and record-keeping requirements.
| Feature | STH-3 (Manual) | STH-3A (Touchscreen) | STH-5 (Gradient) |
|---|---|---|---|
| Temperature Range | RT+10 ~ 250°C | RT+10 ~ 250°C | RT+10 ~ 250°C |
| Temp Accuracy | ±1°C | ±0.5°C | ±1°C |
| Sealing Pressure | 0.1–0.7 MPa | Automatic | 0.1–0.7 MPa |
| Test Positions | 1 | 1 | 5 (gradient) |
| Seal Jaw | 300 × 10 mm | 300 × 10 mm | 5 × (40 × 10 mm) |
| Control Type | Manual | Touchscreen | Digital display |
| Test Records | Manual record | Built-in printer | Manual record |
| Best For | Small R&D labs | Documented routine QC | Film R&D / seal window mapping |
| ASTM F88 | ✓ | ✓ | ✓ |
| ASTM F2029 | ✓ | ✓ | ✓ |
Frequently Asked Questions
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