Classifying Pressure-Controlled Valves

The method for simulating the reed typically depends on whether an additional upstream or downstream pressure causes the corresponding side of the valve to open or close further.

As per Fletcher, the couplet $(\sigma_1, \sigma_2)$ may be used describe the upstream and downstream valve behaviour, respectively.

A $\sigma_n$ value of

• +1 indicates an opening of the valve,
• -1 indicates a closing of the value,

on side $n$ in response to a pressure increase.