An automatic door bottom advertised for fire doors still requires exact product and opening review. NGP's model 320 sheet includes particular positive-pressure and Category H information; UL separately warns that leakage-rated results, installation conditions and the test treatment of the bottom edge must be checked at the assembly level.
Manufacturer documents and safe interpretation
- NGP’s dated model 320 sheet has Category H and fire-door application statements for this named model, not for every automatic door bottom. Publisher document — PDF p.1, product 320 mark and printed Category H text.
- The same model 320 instruction states a maximum drop of five-eighths inch for that document’s installation context. Publisher document — PDF p.2, step 8, Maximum drop 5/8-in.
- UL instructs users to consider the certified leakage-rated assembly’s specific component and installation information. Publisher document — printed p.15 Section 2.E leakage-rated assembly instructions.
- UL cautions that leakage test artificial-bottom-seal conditions cannot reliably be inferred from the door assembly marking alone. Publisher document — printed pp.15-16 Artificial bottom seals.
How to make the distinction
A listing-check packet, not an adjustment recipe
| Evidence field | What to copy for qualified review | Why leave blank if unknown? |
|---|---|---|
| Installed door/frame labels | Identifier and observed rating markings | Generic bottom-product certification does not identify the door |
| Candidate automatic bottom | Exact model and manufacturer's dated instruction sheet | Other NGP products or generic drop bars are not model 320 |
| Category/test references | Product-specific fire/smoke claims and conditions | Do not expand a product claim beyond the original sheet |
| Door-bottom testing information | Assembly manufacturer's leakage-rated instructions; artificial-seal condition when applicable | The visible assembly label need not disclose that test choice |
National Guard Products model 320 Installation Instructions (edition 08.25, PDF p. 2, step 8) state a maximum 5/8-inch drop for that model’s documented installation sequence. That figure is not an adjustment target for an unidentified existing door, nor approval to modify a rated-door assembly. Use the labeled opening’s approved service documentation and a qualified reviewer.
Reader checklist: identification and safe handoff
- Record existing door, frame and bottom-product identifiers without disassembly.
- Collect the candidate manufacturer's complete dated manual, plus the installed door's certified assembly instructions.
- Have a qualified fire-door reviewer confirm category, location, leakage-test conditions, latching and permissible hardware configuration.
- If any record conflicts, postpone replacement; do not trim a door, add a bar or change plunger settings on this guide's authority.
What the evidence does—and does not—settle
Supported: a four-document decision record for a named automatic bottom. Not supported: exact fit, installation approval, permitted adjustment range for the installed door or assembly compliance.