@pipeworx/nist-fluid-properties

Density, viscosity, thermal conductivity, speed of sound, enthalpy, entropy, Cv/Cp and phase for ~76 reference fluids — water, nitrogen, oxygen, argon, carbon dioxide, light hydrocarbons, and common refrigerants (R11-RC318) — at a caller-given temperature and pressure, or along the liquid/vapor saturation curve. Every value carries its unit.

Part of Pipeworx — an MCP gateway connecting AI agents to 1851+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Tools

• nist_fluid_properties(fluid, temperature, temperature_unit?, pressure, pressure_unit?) — density, specific volume, internal energy, enthalpy, entropy, Cv, Cp, speed of sound, Joule-Thomson coefficient, viscosity, thermal conductivity and phase (liquid/vapor/supercritical) at one temperature/pressure point.

• nist_fluid_saturation(fluid, temperature? OR pressure?, temperature_unit?, pressure_unit?) — give a saturation temperature (returns the matching saturation pressure) or a saturation pressure (returns the matching saturation temperature), plus liquid- and vapor-side density, enthalpy, entropy, viscosity, thermal conductivity and surface tension on the phase boundary.

• nist_fluid_list(query?) — the ~76 fluids this pack covers, optionally filtered by a substring of the name or refrigerant code. An unrecognized fluid argument to either of the tools above also returns this same list.

Related MCP server: pyResToolbox MCP Server

Auth

Keyless.

Data sources

• NIST, Chemistry WebBook SRD 69 — Thermophysical Properties of Fluid Systems. A public, keyless web form; every call proxies it live. The only thing this pack bakes in is a ~76-row fluid-name-to-NIST-id lookup table (not the measurements) so a caller can say "water" or "R134a" instead of NIST's internal identifier.

Notes

• "Air" is not in this dataset as a single fluid. NIST's own fluid- property form does not carry a pseudo-pure "air" entry — query nitrogen, oxygen and argon separately if that's what you need.

• Fluid names, formulas and refrigerant codes are all accepted and matched loosely (case/space/hyphen-insensitive): "water", "H2O", "co2", "Carbon Dioxide", "R134a", "r-134a" all resolve.

• Requesting a condition outside a fluid's valid range (below its triple point, past its upper temperature/pressure limit, or an otherwise unstable point) comes back from NIST as a range error — surfaced as a user_error: with a suggestion to try a condition nearer standard temperature/pressure.

• Viscosity is returned in cP, which is numerically identical to mPa·s (1 cP = 1 mPa·s) — no conversion needed if your use case wants SI.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "nist-fluid-properties": {
      "url": "https://gateway.pipeworx.io/nist-fluid-properties/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/nist-fluid-properties/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1851+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/nist_fluid_properties \
  -H 'Content-Type: application/json' \
  -d '{"fluid":"water","temperature":25,"temperature_unit":"C","pressure":1,"pressure_unit":"atm"}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/nist_fluid_properties. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Standalone (no gateway account)

This package also runs as a local stdio MCP server — no Pipeworx account, no gateway round-trip:

{
  "mcpServers": {
    "nist-fluid-properties": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-nist-fluid-properties"]
    }
  }
}

Or run it directly to confirm it starts:

npx -y @pipeworx/mcp-nist-fluid-properties

It speaks MCP over stdin/stdout and answers initialize/tools/list/tools/call for only this pack's tools — none of the shared meta-tools the gateway connection above adds. Same source, same tools, no ask_pipeworx routing.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Nist Fluid Properties data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides

• pipeworx.io

License

MIT