# Halowerk Fixed-K Rachford-Rice Flash Split

> Halowerk Fixed-K Rachford-Rice Flash Split is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-11-04).

Computes a fixed-K vapor-liquid equilibrium phase split using the Rachford-Rice equation with explicit phase-composition bounds for a mixture.

## Facts

- Endpoint: POST https://detect.halowerk.com/v1/F-TD2000-ENGINEERING-B001/fixed-k-mixture-rachford-rice-equilibrium-phase-split?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-fixed-k-rachford-rice-flash-split-ce0d6032
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_zwUhGtW9bqsugaqrS_Zg-

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability halowerk-fixed-k-rachford-rice-flash-split-ce0d6032 -d '<json body>'
```

Example prompt: Compute the fixed-K Rachford-Rice flash split for a 3-component mixture with overall feed compositions z = [0.3, 0.4, 0.3] and K-values k = [3.5, 0.8, 0.05], and tell me the resulting vapor fraction and phase compositions.

## When to prefer this

Use this endpoint when you have pre-computed or assumed K-values for a multicomponent mixture (up to 24 components) and need to solve the Rachford-Rice flash equation to determine phase split fractions and compositions. This is ideal for process simulation steps, separator calculations, or sensitivity studies where K-values are fixed externally (e.g., from a correlation or prior thermodynamic model) and only the phase-split arithmetic needs to be performed. It is not suited for full equation-of-state flash where K-values must be iterated simultaneously.

## Known failure modes

- Feed composition z values do not sum to 1.0 — invalid input
- K-values outside allowed range (0.0001 to 10000) — schema validation error
- Component count below 2 or above 24 — rejected by schema
- Input UTF-8 payload exceeds 16000 bytes — returns unknown without charge
- Computed result exceeds 20000 bytes — returns unknown without charge
- Degenerate mixture (all K-values ≈ 1) where Rachford-Rice has no unique solution
- Trivial solution (fully liquid or fully vapor) returned when feed is outside two-phase region

## How this service works

Compute a fixed-K mathematical flash split with explicit phase-composition bounds.

## Output

Returns the equilibrium vapor fraction (beta), along with the computed mole fractions for each component in the liquid phase (x_i) and vapor phase (y_i), subject to explicit phase-composition bounds. Oversized inputs exceeding 16000 bytes or outputs exceeding 20000 bytes return an unknown result without charge.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "artifact": {
   "type": "object",
   "required": [
    "flash"
   ],
   "properties": {
    "flash": {
     "type": "object",
     "required": [
      "data",
      "claim"
     ],
     "properties": {
      "data": {
       "type": "object",
       "required": [
        "z",
        "k"
       ],
       "properties": {
        "k": {
         "type": "array",
         "items": {
          "type": "number",
          "maximum": 10000,
          "minimum": 0.0001
         },
         "maxItems": 24,
         "minItems": 2
        },
        "z": {
         "type": "array",
         "items": {
          "type": "number",
          "maximum": 1,
          "minimum": 0.000001
         },
         "maxItems": 24,
         "minItems": 2
        }
       },
       "additionalProperties": false
      },
      "claim": {}
     },
     "additionalProperties": false
    }
   },
   "description": "Bounded model; oversized UTF-8 input (16000 bytes) or computed result (20000 bytes) returns unknown without truncation or charge.",
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-fixed-k-rachford-rice-flash-split-ce0d6032/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from detect.halowerk.com](https://www.zero.xyz/host/detect.halowerk.com/llms.txt)