Question 1

What is the difference between the STH-3, STH-3A, and STH-5 heat seal testers?

Accepted Answer

The STH-3 is a single-point manual model for basic QC. The STH-3A adds 5 independent gradient positions and digital controls for ASTM F2029 seal curve mapping. The STH-5 adds a touchscreen, USB/Ethernet data export, recipe storage, and 21 CFR Part 11 audit trail capability.

Question 2

Which heat seal tester model complies with ASTM F88 and ASTM F2029?

Accepted Answer

All three models — STH-3, STH-3A, and STH-5 — fully comply with ASTM F88 and ASTM F2029. The choice depends on your lab's testing volume, gradient needs, and data management requirements.

Question 3

Do I need a gradient heat seal tester or a single-point model?

Accepted Answer

If you test at a single known temperature for routine QC, the STH-3 is sufficient. If you need to map seal initiation temperature (SIT) curves, qualify new films, or optimize seal parameters across a temperature range, choose the STH-3A or STH-5 gradient model.

Question 4

Can I get factory-direct pricing on KHT heat seal testers?

Accepted Answer

Yes. KHT Instrument sells direct from our Shandong facility. Contact us with your packaging material, testing standard, and volume — we provide model recommendations and factory pricing within 24 hours.

Feature	STH-3 (Manual)	STH-3A (Gradient)	STH-5 (Touchscreen)
Temperature Range	0–300°C	0–300°C	0–300°C
Temp Accuracy	±0.5°C	±0.5°C	±0.5°C
Sealing Force	0–600N	0–600N	0–600N
Test Positions	1	5 (gradient)	1 (programmable)
Control Type	Manual dial	Digital LED	7" Touchscreen
Data Logging	Manual record	Manual record	Auto USB/LAN
IoT / Remote	No	No	Yes
Best For	Small R&D labs	Film R&D / QC	Production pharma/battery
ASTM F88	✓	✓	✓
ASTM F2029	✓	✓	✓
ISO 11607	—	Compatible	✓

Heat Seal Tester Models: Compare STH-3, STH-3A, and STH-5

STH-3

STH-3A

STH-5

STH-3 vs STH-3A vs STH-5: Choose Your Model

Frequently Asked Questions

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