Question 1

How do I calculate steam enthalpy online?

Accepted Answer

ChemCalc provides IAPWS-IF97 steam tables for regions 1, 2, and 4 with an explicit Region 3 boundary warning. Enter temperature and pressure to get enthalpy, entropy, specific volume, and quality for saturated or superheated steam. No installation required — runs in your browser.

Question 2

What refrigerants are supported for COP calculations?

Accepted Answer

ChemCalc supports 12 refrigerants: R22, R32, R134a, R125, R152a, R1234yf, R290, R717 (ammonia), R1270, R410A, R600a and R1234ze(E), using Watson-scaled reference enthalpies for preliminary cycle calculations.

Question 3

How do I size a safety valve per API 520?

Accepted Answer

Use the Safety Valve module in ChemCalc. Enter fluid type (gas or liquid), relief pressure, temperature, and flow conditions. The calculator applies API 520 Part I orifice sizing with API 526 letter designations.

Question 4

Can I do VLE flash calculations online?

Accepted Answer

Yes. ChemCalc includes a smart thermo-recommender that auto-routes between Wilson, NRTL, UNIQUAC, UNIFAC, and PR/SRK EOS based on polarity and LLE risk. It covers 454 binary interaction pairs (163 NRTL + 161 Wilson + 130 UNIQUAC) from ChemSep via the thermo MIT library, with 130 components. The AUTO mode picks the best model and shows the reason and accuracy class.

Question 5

Do I need to install ChemCalc?

Accepted Answer

No. ChemCalc runs directly in the browser. You can optionally add it to your home screen as a shortcut, but the calculations do not require a native app or account.

Question 6

How do I calculate cooling tower make-up water?

Accepted Answer

ChemCalc's cooling tower module computes the full water balance: evaporation loss (≈0.00085 × range in °F of circulation per Perry's/GPSA), drift loss, blowdown from the cycles of concentration, and total make-up = evaporation + blowdown + drift. It also returns Merkel NTU, range, approach and tower efficiency.

Question 7

What are the Langelier (LSI) and Ryznar (RSI) indices?

Accepted Answer

ChemCalc's water stability module computes the saturation pH (pHs) from calcium hardness, alkalinity, total dissolved solids and temperature, then reports the Langelier Saturation Index (LSI = pH − pHs) and Ryznar Stability Index (RSI = 2·pHs − pH) with scaling/corrosion interpretation, per Langelier (1936) and Ryznar (1944).

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