Fuel System: Difference between revisions

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'''Note:''' The tank is rated for "Above Ground Only." This is standard for many older LP tanks; it does not preclude installation, but the mounting must support the full weight and allow for thermal expansion.
== Tank Certification and Marking ==


{| class="wikitable"
|-
| '''Status''' || ASME vessel, 1982. Certified to Section VIII, Div. 1. No DOT special permit visible.
|}
=== ASME and DOT marking ===
{| class="wikitable"
|-
! Field !! Value !! Status
|-
| ASME stamp (Section VIII, Div. 1) || <code>U</code> || Confirmed
|-
| U stamp || <code>U</code> || Confirmed
|-
| National Board number || <code>RT3</code> || Confirmed
|-
| DOT special permit / exemption no. || None visible || Confirm with supplier for highway service
|-
| NFPA 58 clearance — fill connection || Not on plate || Ensure 5 ft from ignition sources
|-
| NFPA 58 clearance — fixed level gauge || Not on plate || Ensure 5 ft from ignition sources
|-
| Black diamond PROPANE decal || Not visible || Replace if missing
|}
=== Why these matter ===
* ASME tanks carry '''no requalification cycle''' like DOT cylinders — the plate is the pedigree. If the plate is unreadable, traceability is gone and a filler may refuse it.
* '''"Above Ground Only"''' is a stationary rating. Confirm the ASME stamp and any special permit cover mobile service before the shop plumbs high flow.
* Any welding on the pressure boundary needs a '''commissioned inspector and an R-stamp plate'''. Budget for it if the blower plumbing needs a new bung — no driveway drilling and welding.
=== Plate protection ===
* 44 years old. Protect the plate from corrosion and abrasion or the traceability is lost.
* Photograph and transcribe before any cleaning. Do not scrub the stamping.
* If pitted, log as a problem — an unreadable plate is a tank a filler can refuse.
=== Documentation ===
Photos filed: tank data plate (confirmed), stamp block close-up (confirmed), decal location (pending).


=== Factory vs. conversion ===
=== Factory vs. conversion ===

Revision as of 07:40, 30 October 2026

Fuel System

Status LPG confirmed. Factory vs. conversion unverified — pending Marti deluxe report. Blower fuel spec open.

Overview

The bus runs on LPG. Current hardware is stock naturally-aspirated: a single Impco CA425 mixer on a cast-style mount, single Model E vaporizer. Neither is adequate for the blower build.

Tank Specifications

Field Value Notes
Manufacturer BRUNNER ENG. & MFG. CO. Bedford, Indiana
Capacity 80.8 GAL Water capacity (W.C.)
Serial Number AF5255
Manufacture Year 1982
Max Working Pressure 312 psi
Service Temperature 450°F
Tare Weight 324.32 lbs
Outer Diameter 18.0 in
Length 77 in
Head Thickness .187 in
Application FOR LP GAS ONLY

Tank Certification and Marking

Status ASME vessel, 1982. Certified to Section VIII, Div. 1. No DOT special permit visible.

ASME and DOT marking

Field Value Status
ASME stamp (Section VIII, Div. 1) U Confirmed
U stamp U Confirmed
National Board number RT3 Confirmed
DOT special permit / exemption no. None visible Confirm with supplier for highway service
NFPA 58 clearance — fill connection Not on plate Ensure 5 ft from ignition sources
NFPA 58 clearance — fixed level gauge Not on plate Ensure 5 ft from ignition sources
Black diamond PROPANE decal Not visible Replace if missing

Why these matter

  • ASME tanks carry no requalification cycle like DOT cylinders — the plate is the pedigree. If the plate is unreadable, traceability is gone and a filler may refuse it.
  • "Above Ground Only" is a stationary rating. Confirm the ASME stamp and any special permit cover mobile service before the shop plumbs high flow.
  • Any welding on the pressure boundary needs a commissioned inspector and an R-stamp plate. Budget for it if the blower plumbing needs a new bung — no driveway drilling and welding.

Plate protection

  • 44 years old. Protect the plate from corrosion and abrasion or the traceability is lost.
  • Photograph and transcribe before any cleaning. Do not scrub the stamping.
  • If pitted, log as a problem — an unreadable plate is a tank a filler can refuse.

Documentation

Photos filed: tank data plate (confirmed), stamp block close-up (confirmed), decal location (pending).

Factory vs. conversion

Believed factory or ship-through — unverified.

Supporting evidence:

  • Cast-style mixer mount, no obvious aftermarket adapter plate
  • DSO special order tag (DSO 74 / SO 3152) — see Chassis Documentation
  • Fleet options (traction sanders, tow hooks) consistent with a municipal/district order

Do not log as fact until the Marti invoice confirms. If it shows a ship-through or upfitter conversion, log as "factory-ordered LPG conversion" and cite the line.

Current hardware

Component Current Adequate for boost?
Mixer Impco CA425 (single) No — sized for NA
Vaporizer Impco Model E (single) No — will starve and ice
Lockoff Unknown — inspect Unknown — must be sized for combined flow
Tank Unknown — inspect and record Unknown
Plumbing Unknown — inspect and record Unknown

Blower fuel plan

  • Dual Model E vaporizers, boost-referenced. One E cannot vaporize the airflow at target power; a starved vaporizer ices, pressure collapses, and the engine goes lean under load.
  • Reference both E's to manifold pressure from a common source with equal-length lines — not two separate taps, or the units fight and deliver unevenly.
  • Parallel liquid feed from a common supply with a shared lockoff rated for combined flow. A single-E lockoff becomes the bottleneck.
  • Parallel coolant feed off the heater circuit, split so the rear unit is not downstream of the front unit's heat load. Marginal coolant flow ices a correctly-sized vaporizer.
  • Dual mixers into a common plenum with a fabricated dual-plate adapter. A single CA425 chokes a blown big block — rich at idle, lean at load.
  • Mixer sizing is driven by airflow at target boost. Specify with the shop, not by guesswork.

Open items

  • Tank size, mounting, and liquid-vs-vapor withdrawal — inspect and record
  • Lockoff model and line size — inspect and record
  • Whether the current mixer mount is a bolt-on or fabrication pattern for the new adapter
  • Factory vs. conversion — Marti deluxe
  • Compression and cam — shop measures before boost selection; LPG engines run higher static compression than gasoline, do not assume gasoline figures

Safety and inspection notes

  • Bag the mixer throat and vaporizer before any pressure washing.
  • Photograph the mixer mount from multiple angles before disturbing it — it is evidence for the factory question.
  • Record the existing single E and CA425 as spares or patterns; neither goes back on a blown engine.

Documentation

Photos filed: mixer and mount, vaporizer, lockoff (pending), tank and plumbing (pending).

See also

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