traditional gauges are not suitable for high temp. services of 500 degree C. What provision is for pressure measurement by gauge on 500 degree C temperature?
Standard practice (for an air temperature measurement system) is to include a foot of tubing between the source and the sensor for every 100 degF of temperature. If this is an air system, it will require a minimum of 9 feet of tubing. You will also want to ensure that the sensor is located above the source, so that any condensate in the tubing will drain away from the sensor.