NMX‑FRT‑30 / Rev 00 / fire testing / furnace · restraint · R, E, I 2026 · Product Page

NMX-FRT-30 · ENGINEERED TO ORDER — FIRE RESISTANCE TEST RIG

Not whether it burns. How long it holds.

Name: Fire Resistance Test Rig
Brand: Neometrix

Fire resistance is a duration, not a temperature. The question is never whether an element burns, or how fast flame spreads across it, but how many minutes it keeps doing its job while a standard fire burns on one side. And that number is worthless unless the fire was the same fire every other laboratory used — which is why the furnace's real product is a repeatable fire, not heat. So the rig is built around the things that make it repeatable: a lining light enough to follow the curve's steep opening minutes, plate thermometers instead of bare junctions, controlled furnace pressure, no flame playing on the specimen, and a restraint frame that holds the element the way the building does. Then three criteria decide it — R, E and I — and the useful answer is which one failed, and at what minute. No delivered rig is claimed.

Enquire — fire resistance test rig Capability sheet (PDF)

Illustrative image, not a delivered system — a vertical fire resistance test furnace in an industrial hall seen from the unexposed side: a plain flat test panel mounted in a heavy steel restraint frame bolted to the furnace face, small round disc thermocouple pads taped in a regular grid across the pale panel with thin wires gathered sideways into a loom, two slim displacement transducers on tripod floor stands, the insulated furnace body and flue ductwork behind, cold and unattended, no flame, no people and no markings

Fig · 01 The unexposed side — where the insulation criterion is decided, one bonded thermocouple at a time — illustrative, not a delivered system

Answers

how longminutes, not degrees

The curve

ISO 834BS 476 · IS 3809

Sensed by

plate thermometersnot bare junctions

Controlled

furnace pressure~20 Pa, high up

Verdict

R · E · Iand which failed

ISO 9001 / 14001 Engineered to order Fired-furnace franchise Calibrated & documented Noida · India

Overview

The furnace's product is a repeatable fire.

Every other requirement follows from that. A rating in minutes is a claim made to a certifying authority and defended for the life of a product, so the only thing that makes it worth anything is that the exposure was standard — the same steep curve, the same sensing, the same pressure, the same restraint. A rig that heats a specimen enthusiastically but cannot prove how it heated it has produced a number nobody can use.

Illustrative image, not a delivered system — looking into the open chamber of a cold fire resistance test furnace during inspection: a row of round burner openings set low along the pale ceramic-fibre lined side wall, the soft off-white fibre lightly soot-stained, two flat rectangular steel plate thermometers hanging on slim brackets out in the chamber with thin sheathed leads running back through the wall, the heavy hinged door standing open at the left, flat daylight, no fire, no people and no markings

Fig · 02 Cold and open — the fibre lining that lets the chamber follow the curve, and the plate thermometers that decide what “exposed” means — illustrative, not a delivered system

The curve is the specification. The standard cellulosic time–temperature curve — ISO 834, BS 476, IS 3809, EN 1363 — is deliberately savage at the start: roughly 576 °C at five minutes, 842 °C at thirty, 945 °C at sixty. Crucially, the tolerance is set on the area under the curve rather than on peak temperature, because area is what makes one laboratory's result comparable with another's. Where the credible exposure is a fuel fire rather than a building fire, the hydrocarbon curve rises faster and hotter still.

Following it is a thermal-mass problem before it is a burner problem. The opening minutes are the steepest, and a heavy refractory chamber simply lags through them — under-testing the product exactly where a great many failures actually occur. So the lining is ceramic fibre, chosen to have almost no heat to store, and the burner control is tuned for the ramp rather than the hold.

“Exposed” has to be defined, and it is defined by the sensor. A bare thermocouple hanging in the chamber reports the temperature of the gas. The specimen, however, is being cooked mostly by radiation from the lining and the flame. The standards therefore mandate flat plate thermometers, whose mass and surface make them respond the way the specimen does. Substituting bare junctions does not fail an audit loudly — it just quietly changes the severity of every test the rig has ever run.

We provide the furnace, lining, burner and fuel-train integration, restraint frames, loading, instrumentation, control, interlocks, exhaust handling, calibration and commissioning. Foundations, the test hall and the flue are executed with your own civil agencies.

Repeatable

Tolerance on the area

The curve held to a band on area, not peak — which is precisely what lets another laboratory get your number.

Honest

Pressure, not just heat

A controlled gradient across the specimen — without it a rig is not producing comparable results, however hot it gets.

Diagnostic

Which criterion, and when

R, E and I watched together, so the output is a failure mode and a minute rather than a bare pass.

Architecture

Mount it, burn it, watch it, rate it.

The schematic follows the test — the specimen mounted as it is actually built, the curve followed, the three criteria watched together, the rating written in minutes with its failure mode — and shows what the machine consists of underneath: furnace and burners, the sensing and pressure control, restraint and loading, and the unexposed face with the record it produces.

FIG · 03FIRE RESISTANCE RIG ARCHITECTURE · FURNACE + BURNERS / PLATE THERMOMETERS + PRESSURE / RESTRAINT + LOADING / COLD FACE & RECORD

Fig · 03 A duration, not a temperature — and a number another laboratory would also get

Arc · 01

Furnace & Burners

Ceramic-fibre lining of deliberately low thermal mass so the chamber follows the steep opening minutes, with no flame playing on the specimen.

Arc · 02

Plate Thermometers & Pressure

Flat plate thermometers, not bare junctions, and a controlled pressure gradient across the specimen — the two things that define severity.

Arc · 03

Restraint & Loading

A rigid frame that holds the element as the building does, and hydraulic load maintained as the specimen deflects.

Arc · 04

Cold Face & Record

Bonded unexposed-face thermocouples, deflection, timed integrity observations — every channel logged as the evidence pack.

Specifying, upgrading or re-instrumenting a fire-resistance furnace? Send the standard, the element sizes and the ratings you need to reach — a clause-by-clause compliance matrix within two working days · [email protected]

Send tender spec

Specifications

Reference rig, built to the standard.

The parameters below describe a reference rig. Chamber size, orientation, burner capacity, restraint design, loading and instrumentation channel count all follow from three givens: the standard and curve you are testing to, the largest element you need to mount, and the highest rating you intend to reach.

Illustrative image, not a delivered system — a heavy horizontal steel restraint frame standing over the roof opening of a fire resistance test furnace: four short hydraulic jacks in the frame pressing down through square steel spreader plates onto a thick plain concrete floor slab laid across the dark opening, braided hydraulic hoses looping from the jacks to a small wheeled power pack on the floor, bolted beams and tie rods, painted concrete floor, flat grey daylight, cold and unattended

Fig · 04 Horizontal restraint and loading — the load has to be held as the slab deflects, not set once at the start — illustrative, not a delivered system

Where fire-resistance rigs go wrong

A furnace too heavy to follow the curve's opening, which under-tests the first ten minutes. Bare thermocouples in place of plate thermometers, changing the exposure invisibly. No furnace pressure control, so results are neither reproducible nor comparable between laboratories — the single most common gap in an otherwise capable rig. Flame impingement on the specimen, producing a failure at an artefact of the rig rather than a property of the element. Restraint that does not represent the service condition, which can move a rating by a whole class. Load applied once and left while the specimen deflects away from it. Unexposed-face thermocouples poorly placed or poorly bonded, when the insulation criterion is only ever as good as that contact. No calibration or heat-flux verification, so the furnace drifts between tests and nobody finds out. And records that stop at “pass”, when the certifying evidence is the curve, the pressure trace, every channel and the timed observations.

So the discipline runs the other way. Lining chosen for low thermal mass and control tuned for the ramp. Plate thermometers at the standard positions. Pressure controlled and recorded as a first-class measurement. Burners arranged and baffled so the specimen sees radiation, not a jet. Restraint frames designed per element family and documented as part of the result. Loading closed-loop and maintained through deflection. Cold-face pads at the standard grid, properly bonded. Calibration to a schedule. And a report that gives the customer what they actually came for: which criterion failed, at which minute, and what the curve and pressure were doing at the time.

Full specification — expand

System	Fire resistance test rig — furnace, restraint frame, loading, instrumentation, control & evidence pack for rating elements in minutes
Governing Idea	Fire resistance is a duration, not a temperature — and the furnace's product is a repeatable fire
Exposure Curve	Standard cellulosic time–temperature curve — ISO 834 / BS 476 / IS 3809 / EN 1363 (~576 °C at 5 min, 842 °C at 30, 945 °C at 60); hydrocarbon curve option
Curve Tolerance	Held on the area under the curve, not on peak temperature — the property that makes results comparable between laboratories
Lining	Ceramic fibre, low thermal mass — so the chamber can follow the steep opening minutes rather than lag through them
Exposure Sensing	Flat plate thermometers at standard positions — a bare junction reads gas temperature, the specimen experiences radiation
Furnace Pressure	Controlled gradient across the specimen, order of 20 Pa positive near the top, measured and recorded — ranks with temperature control
Burners	Oil or gas, arranged and baffled so no flame plays directly on the specimen; fuel train with flame supervision, purge cycle and fast shut-off
Orientation	Vertical (walls, doors, partitions, glazing, penetration seals) · horizontal (floors, ceilings, loaded beams)
Restraint	Rigid frame reproducing the service condition — restrained and unrestrained constructions can differ by a whole rating class
Loading	Hydraulic jacks with load maintained as the specimen deflects, through spreader plates, closed-loop
Criterion R	Load-bearing capacity — deflection and rate of deflection limits for loaded elements
Criterion E	Integrity — cotton-pad ignition, the 6 mm and 25 mm gap gauges, and sustained flaming on the unexposed face
Criterion I	Insulation — unexposed-face mean rise ≤ 140 K, single point ≤ 180 K above ambient
Rating Output	Minutes — 30 / 60 / 90 / 120 / 180 / 240 — written as EI 120 or REI 90, with which criterion failed first and when
Instrumentation	Plate thermometers, bonded unexposed-face pads at the standard grid, displacement transducers, load cells, furnace pressure — one calibrated time base, full logging
Circuit Integrity	Cable fire-survival variant — energised specimen must keep its circuit alive through the flame for the rated period (IEC 60331)
Safety	Flame supervision, purge and light-off interlocks, emergency fuel shut-off, abort capability, exhaust handling for smoke and products of combustion
The Discipline	One specimen, one shot — the test destroys a full-size build, so an instrumentation failure spoils the build, not merely a reading
Scope Boundary	Ours: furnace & lining, burner & fuel-train integration, restraint, loading, instrumentation, control, interlocks, exhaust, calibration, commissioning, documentation. Bought-in certified: burners, plate thermometers, load cells, transducers, acquisition. Customer's civil agencies: foundations, hall, flue
The Family	Sits beside the delivered fired-furnace work (burners, zones, temperature uniformity) and the site's test-facility controls franchise — a different question asked with familiar hardware
Status	Engineered to order · quoted against a fire-resistance test-rig requirement · no delivered rig is claimed on this page

PDF · 1 page

Fire Resistance Test Rig — Capability Sheet

Tender Response

Send the standard, element sizes & target ratings — compliance matrix in two working days

Variants

One curve, four rigs.

What changes is the orientation, whether the element carries load, and whether the thing being proved is a barrier or a circuit.

Var · 01

Vertical Furnaces

Walls, doors, partitions, glazing and penetration seals — the integrity and insulation workhorse, with restraint frames per element family.

Var · 02

Horizontal Furnaces

Floors, ceilings and loaded beams — adds the load-bearing criterion, with hydraulic loading maintained through deflection.

Var · 03

Circuit-Integrity & Cable Rigs

Cable fire survival to IEC 60331 — the specimen stays energised and must keep the circuit alive through the flame for the rated period.

Var · 04

Upgrade, Re-instrumentation & AMC

Adding pressure control, plate thermometers or modern acquisition to an existing furnace — plus calibration and support.

Applications

Wherever a rating has to be defended.

Manufacturers proving a product, and laboratories proving it for them.

A · 01Building-product manufacturers — doors, panels, seals

A · 02Power & process plants — barriers, penetrations, cable routes

A · 03Cable & electrical accessory makers — circuit integrity

A · 04Certification & third-party test laboratories

A · 05Shipbuilding & offshore — bulkhead and deck divisions

A · 06Product development & materials research

FAQ

Common questions.

Plain-language answers from the engineering team.

Q · 01 What is the difference between fire resistance and flammability?

They answer different questions and are often confused in specifications, which causes real problems at tender stage. Reaction to fire — flammability, spread of flame, smoke and droplet production — asks what a material contributes to a fire: how readily it ignites, how fast flame travels across it, how much smoke it makes. It is a material property, tested on small samples. Fire resistance asks something else entirely: given that there is already a fully developed fire on one side, how many minutes does this assembly keep doing its job? It is a property of a construction, not a material — the same board rates differently depending on the frame, the fixings, the seals and how it is restrained — and it is tested at full size against a standard fire. A steel door is not flammable at all and can still fail fire resistance in twelve minutes because it distorts and lets flame past the seal. Conversely a timber assembly burns, but chars predictably and can hold for ninety minutes. This rig answers the second question, which is why everything about it — full-size specimens, restraint frames, loading, a standard curve — is built around reproducing a real fire on a real construction rather than characterising a sample.

Q · 02 Why must the furnace follow a fixed curve rather than just get hot?

Because a rating is a comparison, and a comparison needs a fixed reference. “EI 120” means the element behaved a certain way against the standard fire — if each laboratory ran its own fire, the number would carry no information across a border, a supply chain or a certificate. So the standards fix a time–temperature curve. The common one is the cellulosic curve of ISO 834, BS 476, IS 3809 and EN 1363, which approximates a fully developed compartment fire in a building full of ordinary combustibles, and it is steep at the start — about 576 °C by five minutes, 842 °C by thirty, 945 °C by sixty. Two subtleties matter. First, the tolerance is on the area under the curve rather than on instantaneous temperature: a furnace that overshoots and then undershoots has not delivered the standard fire even if it touched every target. Second, the early steepness is where cheap furnaces fail — a heavy refractory chamber cannot ramp that fast, so it quietly under-tests the first ten minutes, which is exactly where seals intumesce, glazing crazes and gaps open. Where the credible fire is a fuel spill rather than furniture, a hydrocarbon curve is used instead, rising faster and hotter, and the rig must be specified for it from the start.

Q · 03 Why plate thermometers instead of ordinary thermocouples?

Because the specimen and a bare thermocouple are not heated by the same thing. A bare junction is a tiny bead with almost no area; it exchanges heat mainly with the gas flowing past it, so it reports something close to gas temperature. The specimen is a large flat surface facing a glowing lining and flame, so it is heated overwhelmingly by radiation. In a chamber where gas and lining are at different temperatures — which is always, especially during the ramp — those two numbers diverge substantially. Control the furnace on the bare junction and the specimen may be receiving far more or far less heat flux than the standard intends. The plate thermometer was introduced to close exactly this gap: a flat steel plate with insulation behind it, sized and mounted so that its response to radiation and convection mimics the specimen's. It is deliberately slower and deliberately radiation-weighted. The practical consequence is blunt: a furnace controlled on plate thermometers and one controlled on bare junctions are running different tests, and results from the two are not comparable. It is also the most common quiet non-conformity we are asked to correct on existing rigs, usually alongside the absence of pressure control.

Q · 04 Why does furnace pressure matter so much?

Because integrity failures are driven by pressure difference, not by temperature alone. Hot gas in a furnace is buoyant, so a chamber left to itself develops a pressure gradient: negative low down, positive high up, with a neutral plane somewhere between. Where the specimen sees positive pressure, hot gas is pushed through any joint, crack or seal gap; where it sees negative pressure, cool air is drawn in and the same defect passes unnoticed. Move the neutral plane and you change the answer. The standards therefore specify the gradient — typically the neutral plane low in the furnace so that most of the specimen sits slightly positive, on the order of 20 Pa near the top — and require it to be measured and maintained throughout. A rig without controlled pressure is not merely less precise; it is producing results that cannot be compared with anyone else's, and which will move between tests as the flue, the weather and the burner setting change. Achieving it needs a controlled exhaust damper, a pressure probe at the standard height and a control loop that holds the setpoint while the burners are chasing a steep ramp — which is why it is the thing most often left out, and the first thing we add on an upgrade.

Q · 05 What exactly are R, E and I, and why report which one failed?

They are the three jobs a fire-separating element might have, judged independently and simultaneously. R — load-bearing capacity: for a loaded floor, beam or column, does it still carry its load? Judged on deflection and rate of deflection limits, so that collapse is anticipated rather than merely recorded. E — integrity: does it stop flame and hot gas crossing? Judged by whether a cotton-wool pad held against a gap ignites, whether the 6 mm and 25 mm gap gauges can be passed through, and whether there is sustained flaming on the unexposed face. I — insulation: does the unexposed face stay cool enough that things touching it do not ignite? Judged on a mean rise of 140 K with no single point above 180 K. A rating is written by combining them — EI 120 for a non-loadbearing wall holding integrity and insulation for two hours, REI 90 where load-bearing is included. Reporting which criterion failed and at what minute is the whole value of the test to a manufacturer: failing I at 95 minutes because the cold face got hot is a different engineering problem, with a different and usually cheaper fix, from failing E at 95 minutes because a seal opened.

Q · 06 What do you build, and what is bought in?

Divided honestly, because a fire-resistance rig is mostly structure, control and discipline rather than exotic hardware. What Neometrix provides: the furnace — shell, casing, ceramic-fibre lining and door; the burner arrangement and fuel-train integration, including baffling so no flame plays on the specimen, flame supervision, purge and light-off interlocks and emergency shut-off; the restraint frames, designed per element family, which are more of the engineering than people expect; the hydraulic loading system with load maintained through deflection; the instrumentation layout — plate thermometer positions, the unexposed-face pad grid, displacement transducers, furnace pressure probe; the control and acquisition that tracks the curve to tolerance on area while holding pressure, and logs every channel on one time base; exhaust handling; and calibration, commissioning, training and AMC plus the evidence pack. What is bought-in certified: burners, plate thermometers and thermocouples, load cells, displacement transducers, acquisition hardware and any gas analysis. What runs with your own civil agencies: foundations, the test hall and the flue stack. Engineered to order; quoted against a fire-resistance test-rig requirement; no delivered rig is claimed on this page.

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Get a quotation

Send the standard
and the rating.

The projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — fire resistance test rig Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — FIRE RESISTANCE TEST RIG THE CURVE HELD ON AREA · PLATE THERMOMETERS · CONTROLLED PRESSURE · R, E AND I ENGINEERED IN NOIDA · INDIA

Not whether it burns. How long it holds.

The furnace's product is a repeatable fire.

Tolerance on the area

Pressure, not just heat

Which criterion, and when

Mount it, burn it, watch it, rate it.

Furnace & Burners

Plate Thermometers & Pressure

Restraint & Loading

Cold Face & Record

Reference rig, built to the standard.

Where fire-resistance rigs go wrong

One curve, four rigs.

Vertical Furnaces

Horizontal Furnaces

Circuit-Integrity & Cable Rigs

Upgrade, Re-instrumentation & AMC

Wherever a rating has to be defended.

Common questions.

The fire & thermal family from Neometrix.

Hangar Fire Test Facility

Fired Billet Reheating & Heat Treatment Furnace

Climatic & Environmental Test Chambers

Send the standard
and the rating.

Similar Products

Share This Page

Not whether it burns. How long it holds.

The furnace's product is a repeatable fire.

Tolerance on the area

Pressure, not just heat

Which criterion, and when

Mount it, burn it, watch it, rate it.

Furnace & Burners

Plate Thermometers & Pressure

Restraint & Loading

Cold Face & Record

Reference rig, built to the standard.

Where fire-resistance rigs go wrong

One curve, four rigs.

Vertical Furnaces

Horizontal Furnaces

Circuit-Integrity & Cable Rigs

Upgrade, Re-instrumentation & AMC

Wherever a rating has to be defended.

Common questions.

The fire & thermal family from Neometrix.

Hangar Fire Test Facility

Fired Billet Reheating & Heat Treatment Furnace

Climatic & Environmental Test Chambers

Send the standardand the rating.

Similar Products

Share This Page

Send the standard
and the rating.