Compression factor = 1 is used for chosen set of base conditions

What causes this issue?

The conversion group for natural gas processing is set to use real gas
formulas. However, for the specified set of base conditions, the real
gas compression factor of dry air is not defined exactly and will be set
to <ZH>1</> by the system.

System Response

This message can be customized to appear as a warning, error or
information message (Trans. O591).

How to fix this error?

If you want to use a more accurate compression factor, you can use
method DETERMINE_Z_FACTOR of BAdI OIB_QCI_NATURAL_GAS to provide this
factor for the calculation. If <ZH>1</> is a sufficiently accurate value
for your calculations, you can change the message type of this message
so that it does not appear any more.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.