# Process Units Conversion

> >-

- **Type:** Skill
- **Install:** `agentstack add skill-jskherman-engg-skills-process-units-conversion`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [jskherman](https://agentstack.voostack.com/s/jskherman)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [jskherman](https://github.com/jskherman)
- **Source:** https://github.com/jskherman/engg-skills/tree/main/skills/process-units-conversion

## Install

```sh
agentstack add skill-jskherman-engg-skills-process-units-conversion
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Process Units Conversion

## Overview

Deterministic unit conversions for the common process-engineering
quantities (flow, pressure, viscosity, thermal conductivity, energy,
temperature, length, area, volume, density, mass). All calculations are
SI under the hood; converting to or from a non-SI unit goes through the
SI value.

## Prerequisites

1. `uv` available.

## When to Use

- An input is given in psia, bar, lbm/hr, gpm, cP, ft, in, etc., and you
  need SI before calling another skill.
- The user requests output in non-SI units (e.g. shop-floor reporting).
- You need to sanity-check a vendor data sheet expressed in mixed units.

## Don't use for

- Computing properties that depend on state (density, viscosity, heat
  capacity) — those need a property package (`thermo-process-properties`).
- Currency, financial, or non-physical conversions.
- Unit groups that are NOT pure conversions (e.g. API gravity to density
  depends on water reference; check the underlying definition).

## Utility Scripts

- `uv run scripts/convert_units.py convert --value 100 --from-unit psi --to-unit Pa --output /tmp/p.json`
- `uv run scripts/convert_units.py convert --value 2.5 --from-unit gpm --to-unit m3_s --output /tmp/q.json`
- `uv run scripts/convert_units.py list-units --output /tmp/units.json`

## Procedure

1. Identify the source unit and the target unit.
2. Confirm the conversion is purely dimensional (no T/P/composition
   dependence).
3. Run the script; inspect the JSON for the SI value as well.
4. If the result is suspicious (off by a factor of 10), check whether you
   confused similar units (e.g. psia vs psig, bar vs barg, mol/h vs kmol/h).

## Pitfalls

- Treating gauge pressure (psig, barg) as absolute (psia, bara). The skill
  is unit-of-quantity, not gauge-vs-absolute; you must subtract / add
  atmospheric pressure yourself.
- Mixing mass and molar flow ("kg/s vs kmol/s"); they are different
  dimensions and the skill will refuse them.
- Treating "Bbl" or "STB" without specifying the reference (oil vs water).
- Treating Celsius and Kelvin as interchangeable for delta-T calculations
  (they are; for absolute, they are not). Convert intentionally.
- Treating cP and cSt as the same; cP is dynamic viscosity, cSt is
  kinematic viscosity (= dynamic / density).
- Converting GPM to m³/s and forgetting US-vs-Imperial gallons.
- Inputting flow in "mol%" when the schema expects mole fraction.
- Reporting a converted value with more digits than the source warrants.

## Fallback Strategies

- If the requested unit is not in the registry, surface to the user; do
  NOT guess the conversion factor.
- For non-trivial conversions (e.g. API gravity, gas SCF at standard
  conditions), use a dedicated property routine instead.

## Verification

- Run the listed script with representative inputs and an `--output` file when a deterministic calculation is available.
- Confirm the JSON result contains `ok: true`, expected units, and no unhandled warnings.
- Check result magnitudes against the stated assumptions, references, and a hand calculation or known operating range before reporting them.

## References

- `references/unit_conventions.md` — supported quantities and units.

## Anti-Patterns

- Embedding a "convenient" conversion factor in another script instead of
  routing through this skill.
- Reporting bar and psi values together without naming gauge vs absolute.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [jskherman](https://github.com/jskherman)
- **Source:** [jskherman/engg-skills](https://github.com/jskherman/engg-skills)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-jskherman-engg-skills-process-units-conversion
- Seller: https://agentstack.voostack.com/s/jskherman
- Browse the marketplace: https://agentstack.voostack.com/browse

---
Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.