Is the selection of temperature category for electrical equipment related to process temperature?
Thread Content
The hazardous medium is acetaldehyde, and the temperature category is T4. I would like to choose a Yokogawa AGX electromagnetic flowmeter; the explosion-proof certification for this flowmeter is shown in the diagram. The selected temperature category is T6, and the process temperature can reach up to 75°C. If the temperature of my medium is above 75°C, can’t I use T6 then? Does the process temperature here refer to the medium temperature?
T4 and T6 refer to the ambient temperature, right? They have nothing to do with the temperature of the medium. As I understand it, T4 and T6 both indicate the external ambient temperature required for the instrument to operate stably. The medium temperature affects the primary components, right?
If the temperature of the medium is high, you can measure the temperature on the surface of the flow meter and then determine whether T6 can be used
The temperature class of explosion-proof electrical equipment refers to the highest surface temperature that the equipment can generate under fault conditions.
Similarly, it can be understood that at this temperature, flammable and explosive gases cannot be ignited……
The original poster has a misunderstanding; my personal understanding is as follows: The hazardous medium in question is acetaldehyde, and the temperature category is T4. This means that the substance being used is acetaldehyde, with a flash point of 120 degrees (ignition temperature: 140°C). When choosing an electromagnetic flowmeter, it is necessary to take into account the possibility of acetaldehyde gas present in the air; the temperature of the flowmeter’s housing must not exceed 120 degrees, otherwise the high temperature could cause the acetaldehyde gas in the air to ignite. Therefore, the housing temperature of your electromagnetic flowmeter must not exceed 120 degrees; thus, a grade of T4 or higher is required, such as T5 or T6. The temperature should not reach the ignition point or flash point of acetaldehyde, which is 120 degrees (ignition temperature: 140 degrees is sufficient)
It is sufficient to ensure that the temperature category meets the requirements. The temperature category represents the highest surface temperature that can be reached under the most unfavorable conditions of the equipment; in other words, no higher temperature is possible.
How can the shell temperature be kept below 120°? What technology is used to achieve this? Even if the housing is heated directly, will the temperature still not exceed 120°?
Temperature category refers to the condition in which the surface temperature of electrical equipment will not exceed that temperature under any circumstances. The temperature category of a process medium refers to the temperature at which it can be detonated (ignited) by that medium. When selecting the temperature category for electrical equipment, it should be lower than that of the process medium, thereby ensuring that the electrical equipment will not cause the process medium to explode.
Explosion-proof technology can be achieved! Specifically, learn the basics of explosion protection regarding intrinsically safe, flameproof, enhanced safety, positive pressure, and sealed designs. Many electromagnetic flowmeters are powered by 220V AC; in the event of an electrical short circuit, very high temperatures can be generated – temperatures exceeding 120 degrees – and this can even lead to fires and explosions!