# Neqsim Dry Gas Seal Screening

> Educational dry gas seal supply and condensation screening for centrifugal compressors. USE WHEN: a task needs a public, screening-level estimate of seal-gas and separation-gas supply demand and a seal-gas condensation-margin check (cavity temperature versus hydrocarbon dew point) before detailed dry gas seal system design per API 692.

- **Type:** Skill
- **Install:** `agentstack add skill-equinor-neqsim-community-skills-dry-gas-seal-screening`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [equinor](https://agentstack.voostack.com/s/equinor)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [equinor](https://github.com/equinor)
- **Source:** https://github.com/equinor/neqsim-community-skills/tree/main/skills/process/dry-gas-seal-screening
- **Website:** https://equinor.github.io/neqsimhome/

## Install

```sh
agentstack add skill-equinor-neqsim-community-skills-dry-gas-seal-screening
```

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

## About

# Dry Gas Seal Screening

Use this skill for public, educational dry gas seal screening on centrifugal compressors. It estimates the seal-gas and separation-gas supply demand from the primary seal leakage rate and flags retrograde-condensation risk by comparing the seal cavity temperature against a hydrocarbon dew point at the seal/vent reference condition.

## When to Use

- When a user asks whether a compressor dry gas seal has adequate seal-gas supply margin.
- When an agent needs a quick condensation-risk triage for the primary vent / standpipe dead-leg before a detailed seal study.
- When examples must run without confidential seal vendor data, machine line lists, or project seal-gas conditioning specifications.

## Inputs

- `seal_leakage_rate_nl_per_min`: primary seal leakage rate at standard conditions in NL/min per seal.
- `seal_cavity_temperature_c`: seal cavity (process-side) temperature in degrees C.
- `hydrocarbon_dew_point_c`: hydrocarbon dew point at the seal/vent reference condition in degrees C.
- `seal_count`: number of seals supplied (default 2: drive end and non-drive end).
- `supply_margin`: seal-gas supply margin over leakage, dimensionless, default 1.25.
- `separation_gas_rate_nl_per_min`: separation (secondary) gas rate per seal in NL/min, default 0.0.

## Outputs

- `total_seal_gas_supply_nl_per_min`: screening seal-gas supply demand.
- `separation_gas_supply_nl_per_min`: screening separation-gas supply demand.
- `seal_gas_supply_margin_ratio`: the applied supply margin over leakage.
- `condensation_margin_c`: seal cavity temperature minus the hydrocarbon dew point.
- `condensation_warning`: `ok`, `watch`, or `high` (a small or negative margin means higher condensation risk).
- `assumptions`: public assumptions used by the placeholder model.

## Engineering Method

The Python class `DryGasSealModel` uses open, public concepts only:

- seal-gas supply demand is the primary seal leakage multiplied by the seal count and a supply margin, reflecting the API 692 intent that supply must exceed leakage to keep the seal faces clean.
- separation-gas supply demand scales with the seal count.
- the condensation margin compares the seal cavity temperature against a hydrocarbon dew point at the seal/vent reference condition. A small or negative margin flags retrograde condensation risk in the primary vent piping and standpipe dead-legs, which is the failure mode that seal-gas conditioning units exist to prevent.

This is educational and screening-only logic. It is not a seal vendor method, not a seal-gas conditioning design, and not a replacement for validated dry gas seal analysis and a qualified rotating-equipment review.

## Python Usage Pattern

```python
from dry_gas_seal_screening import DryGasSealModel

model = DryGasSealModel()
result = model.evaluate(
    seal_leakage_rate_nl_per_min=280.0,
    seal_cavity_temperature_c=44.0,
    hydrocarbon_dew_point_c=40.0,
    seal_count=2,
    supply_margin=1.25,
    separation_gas_rate_nl_per_min=120.0,
)

print(result.condensation_warning)
print(result.total_seal_gas_supply_nl_per_min)
print(result.condensation_margin_c)
```

If the optional `neqsim` Python package is available, the result records that fact so an agent can recommend moving to validated NeqSim seal-gas dew-point and condensation analysis. If it is not installed, the example still runs with public placeholder logic.

## Validation Checklist

- [ ] Inputs are in the documented units (NL/min, degrees C).
- [ ] Example inputs are public and synthetic.
- [ ] Tests cover ok, watch, high, and invalid-input cases.
- [ ] Results are described as educational screening indicators.
- [ ] Real seal system design is redirected to validated methods, API 692, and qualified review.

## Common Mistakes

| Symptom | Cause | Fix |
| --- | --- | --- |
| Condensation never flagged | Dew point taken at cavity pressure instead of the vent/expanded condition | Use the hydrocarbon dew point at the seal/vent reference condition |
| Supply demand looks low | Supply margin set to 1.0 | Use a supply margin above 1.0 consistent with the seal-gas control philosophy |
| Wrong total supply | Seal count not matching the machine arrangement | Set `seal_count` to the actual number of seals supplied |

## Limitations

- No seal vendor leakage curves, clearance models, or qualification data are included.
- No isenthalpic (Joule-Thomson) expansion or transient standpipe cooldown is modelled.
- No seal-gas conditioning unit (heater/separator) sizing is performed.
- Not suitable for safety-critical, design, guarantee, or standards-compliance work.

## Related NeqSim Functionality

This educational screening corresponds to validated, rigorous functionality in the NeqSim Java library that a qualified engineer should use for design-grade work:

- `neqsim.process.equipment.compressor.DryGasSealAnalyzer` — isenthalpic seal-gap expansion, retrograde condensation mapping, dead-leg cooldown, condensate accumulation, and seal-gas conditioning unit sizing per API 692.
- `neqsim.process.measurementdevice.HydrocarbonDewPointAnalyser` — hydrocarbon dew-point evaluation for the seal-gas stream.
- `neqsim.process.equipment.valve.ThrottlingValve` — Joule-Thomson expansion modelling across the seal gap.

In Python the same classes are reachable through the `neqsim` package (for example `from neqsim import jneqsim`).

## References

- NeqSim repository: https://github.com/equinor/neqsim
- NeqSim Skills Guide: https://github.com/equinor/neqsim/blob/master/docs/integration/skills_guide.md
- Public rotating-equipment references such as API 692 (Dry Gas Sealing Systems) and API 614 (Lubrication, Shaft-Sealing, and Oil-Control Systems) for general seal-gas concepts.

## Source & license

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

- **Author:** [equinor](https://github.com/equinor)
- **Source:** [equinor/neqsim-community-skills](https://github.com/equinor/neqsim-community-skills)
- **License:** Apache-2.0
- **Homepage:** https://equinor.github.io/neqsimhome/

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-equinor-neqsim-community-skills-dry-gas-seal-screening
- Seller: https://agentstack.voostack.com/s/equinor
- Browse the marketplace: https://agentstack.voostack.com/browse

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