The position setting of the red line of the pressure gauge.
Thread Content
I have a small question for everyone, and I hope everyone will speak enthusiastically. There are three-color pointers in the pressure gauge head: green needle, black needle, and red needle. My understanding is that the green needle is the lowest operating pressure, the red needle is the highest operating pressure, and the black needle is the actual operating pressure. Please tell me how to set the position of the red line (red needle) of the pressure gauge of the moving equipment? Is there a standard, or how many times the operating pressure? In addition, the position of the red line of the pressure gauge of the container can be set to the design pressure of the tank or tower. Is it possible?
It is set according to the highest value of the process, not the design pressure.
General pressure gauges do not have a red line. We drew it ourselves, which is 1.25 times the operating pressure.
The green needle on the pressure gauge head is the set alarm value, the red needle is the parking value, and the black needle is the actual operating pressure. , the red line of the pressure gauge of the container is the maximum working pressure, which is lower than the design pressure, as specified in GB150
"The position of the red line of the pressure gauge of the container can be set as the design pressure of the tank or tower - in actual use, the operating pressure of any container will generally not reach the design pressure value. Occasionally it may reach it instantaneously or in a short period of time under abnormal conditions, but under normal circumstances it is lower than the design pressure, so the red line of the pressure gauge (maximum operating pressure) should not be set so high.
Normal operating pressure (plus or minus 10%* meter range)
It is set according to the highest value of the process, not the design pressure.
First of all, it is clear that the pressure gauge is installed for the safety of the equipment itself. It serves as a safety accessory of the equipment. The following is a quoted procedure: For pressure gauges installed on pressure vessels, the limit value of the dial scale should be 1.5 to 3 times the maximum working pressure of the vessel, preferably 2 times. The larger the range of the pressure gauge, the greater the absolute value of the allowable error and the greater the visual error. The selection of a pressure gauge should also be based on the pressure level of the container and the work needs. According to the pressure level requirements of the container, low-pressure containers are generally not lower than level 2.5. ； Medium-pressure and high-pressure vessels should not be lower than level 1.5. The pressure gauge in use should have a warning red line drawn on its dial according to the maximum working pressure of the equipment, but do not paint it on the dial glass to prevent the rotation of the glass from causing misunderstandings to the operator and causing accidents. Obviously the red line of the pressure gauge mounted on the container cannot be determined as the design pressure!
What the poster is talking about should be an electric contact pressure gauge, also known as a pressure switch. The green needle is the minimum operating pressure limit, the red needle is the maximum operating pressure limit, and the black needle is the actual operating pressure. Electric contact pressure gauges are commonly used in vacuum pumps. The red lines drawn on the pressure gauge serve as a warning to the operator. These artificial lines are set according to the highest value of the process, not the design pressure.
What you are talking about is an electric contact pressure gauge. The black needle is the actual pressure value, the red needle is the upper pressure alarm value, and the green needle is the lower pressure alarm value. If you still need pressure high and low limit interlocking shutdown, you can set up an electric contact pressure gauge, adjust the red needle pressure to the upper limit interlocking value, and adjust the green needle pressure to the lower limit interlocking value. The upper and lower pressure limit alarms and interlocking are realized through two gauges.
The green needle on the head of the pressure gauge is the set alarm value, the red needle is the parking value, and the black needle is the actual operating pressure.