---
title: Product limitations
description: Rated limits versus sizing — whether an instrument survives the process, and whether it can read the duty.
sidebar:
  label: Product limits
  order: 14
---

Two different questions, often collapsed in conversation:

| Question | Answered by | Example |
| --- | --- | --- |
| Does this instrument **survive** the process? | Product limitations (rated temperature, pressure, viscosity, conductivity, phases) | Conductivity ≥ 5 µS/cm on an EMF |
| Can this instrument **read** the duty? | Flow sizing tables | DN50 at this m³/h is inside the published band |

A wrong bore is often **correctable** (quote DN80 instead). A duty no published
size in the family reaches **rules the family out** (R29).

## Where the limits come from

Flowtech's *Product Limitations & Restrictions Guide* states hard limits in a
consistent grammar, with a **qualifier** when the bound depends on phase,
construction, or flow band:

- `Temperature (Liquid)` versus `(Gas)` versus `(Steam)`
- `Pressure (Standard SS)` versus `(PTFE-Lined)`
- `Pressure (WE < 10,000 LPH)` versus `(WE >= 10,000 LPH)`

Absence of a figure is not a free pass: switch datasheets leave temperature
and pressure blank, so family-level figures are used and a specific model may
be tighter. Verify against the latest datasheet before final selection.

## Kinds

| Guide section | What it means for quoting |
| --- | --- |
| **Hard limits** | Numeric or categorical bounds. A stated breach excludes |
| **Not suitable for** | Duties this family is not for |
| **Key limitations** | Constraints that are not a simple bound |
| **Installation** | Orientation, run-up, probe length |

A breach of an **assumed** value warns; a breach of a **stated** value
excludes (R24).

## Sizing tables

The flow-range tables are not one shape. Some families key by line size, some
by tube × float, some by connection, steam by line size × pressure as **mass**
flow. Steam rows are not converted as if they were water.

For a size-axis family the sizing table's size column *is* the variant axis —
that is how the table drives which item codes exist.

## What the business does here

- Keep the guide and the sizing reference current; a corrected limit changes
  the next recommendation without a code change.
- Do not invent a rating where the guide is silent — the option stays
  unconfirmed (R23).

Related: [Product suggestion](/business/features/product-suggestion) ·
[Reference data](/business/features/reference-data) ·
[Limitations](/business/limitations).