Up to about 150 psig or so. Yes. Graphite is used for shaft seals on steam powered equipment.
30 PSIG is about equal to 45 PSIA. Saturation temperature from the steam tables at 45 PSIA is about 274°F. So the steam would be 274°F, or hotter if superheated.
The saturation temperature of R-410A at 38 psig is approximately 18.5°C or 65.3°F.
The condensing temperature for an R22 system with a head pressure of 296 psig would typically be around 120-130°F. This is based on the saturation temperature corresponding to a pressure of 296 psig on the R22 pressure-temperature chart.
The evaporation temperature of R-134a at 0 psig (or atmospheric pressure) is around -26.2°C (or -15.16°F).
-15 degrees F
This is a dangerous practice - make sure you have a safety valve set at a pressure your stove is certified for. The equilibrium steam/water pressure for temperatures above 100 C is: 110 C - 6psig, 120 C - 14 psig, 130 C - 24.5 psig, 140 C - 37.6 psig, 150 C - 54.3 psig.
psia to psig psig - 15 15 - 15= 0 psig
The condensing temperature for an R-12 system with a head pressure of 175 psig would be approximately 119°F. This is based on typical saturation temperature-pressure relationship for R-12 refrigerant.
psia=psig+atmospheric pressure where, atmospheric pressure = 14.7psi therefore psig=psia-atmospheric pressure psig=100-14.7 psig=85.3psig
Using the ideal gas law equation P1V1 = P2V2, with initial pressure (P1) = 10 psig, initial volume (V1) = 30 ft^3, final volume (V2) = 25 ft^3, we can solve for the final pressure (P2). (10 psig * 30 ft^3) / 25 ft^3 = 12 psig, so the new pressure would be 12 psig.
the blowback or blowdown of the safety valve is at least 2 psi and for pressures over 100 psig is 2% of the popping pressure. The blowback is adjusted with the adjusting ring on the safety valve. The blowback is the pressure less than the popping pressure at which the safety valve will reset. Examples: a safety valve set to pop at 15 psig will reseat at 13 psig, the blowback is 2 psi. A safety valve set to pop at 250 psig will reseat at 245 psig the blowback is 5 psi or 2%.