Since Apple released its new auto-layout language -SwiftUI last July, it is more convienient than before to develop an iOS app, I tried and completed an App called " cryogenics".
You can search it in iphone AppStore.

This app aims to support engineers who worked in air separation or cryogenic industrial.
1- Convert the fluid volume
2- Estimate the properties of mixtures
3- Estimate the pyschrometircs
4- esimate the pressure drop through piping
Feel free to let me know your comments.

See More: iOS App :Pyschrometrics , properties, and pressure drop