# PHS-App — Predicted Heat Strain ISO 7933

> Predicted Heat Strain ISO 7933 (iPhone/iPad app by Vinod Gopaldasani.)

- Source: https://appshunter.io/ios/app/phs-app/id6821626690 (this page in markdown: same URL + `.md`)
- Developer: [Vinod Gopaldasani](https://appshunter.io/developer/867920827)
- Category: Utilities, Productivity
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 5 MB
- Languages: American English
- Released: 2026-10-16
- Data updated: 2026-10-18

## What is PHS?

PHS-App assesses heat stress at work using the Predicted Heat Strain (PHS) model of ISO 7933:2023, the international standard for the analytical evaluation of heat stress.

Describe the worker, the climate, the activity and the clothing, and the app calculates:
• the maximum allowable exposure time, and whether it is limited by body core temperature or by water loss
• rectal temperature and cumulative water loss, minute by minute
• the predicted sweat rate

FEATURES
• Several work phases in sequence (for example work, rest, work). Body temperature and water loss carry over from one phase to the next.
• Enter your own values, or choose from typical activities and clothing ensembles
• Radiant heat as globe temperature or mean radiant temperature; humidity as relative humidity or vapour pressure
• Metabolic rate in W or W/m², with the conversion shown
• Options for acclimatised workers and for workers who can drink freely
• Inputs are checked against the model's validated ranges, with clear warnings
• Charts of rectal temperature and water loss, with limit lines, phase bands and your own notes
• A formatted report you can print, or save and share as a PDF
• Scenarios are saved as .ete2 files in the Files app, ready to share and reopen on other devices; older .ete files can be imported
• Includes the five worked examples of ISO 7933 Annex F
• Works offline. Your scenarios stay on your device.

WHO IT IS FOR
Occupational hygienists, health and safety professionals, engineers and students assessing hot working conditions such as foundries, mines, kitchens, laundries and outdoor work in summer.

IMPORTANT
Results are predictions from the ISO 7933 model for a standard worker. They support, but do not replace, professional judgement, and physiological monitoring where the standard calls for it. This app is not a medical device.

Developed by Vinod Gopaldasani.

## Is PHS safe?

Not enough ratings yet to assess PHS.

## Is PHS legit?

PHS-App appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for PHS is 68 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 1 release)

### 2.0.0 — 2026-10-16

No release notes.

## More apps by Vinod Gopaldasani

- [Thermal Risk](https://appshunter.io/ios/app/thermal-risk/id867920824)

All apps by Vinod Gopaldasani: https://appshunter.io/developer/867920827

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-18.*