What is a negative pressure gauge?

Negative pressure gauges, also known as vacuum negative pressure gauges, vacuum manometers, negative pressure gauges, push-pull gauges, negative-positive pressure gauges,… have the English name Vacuumm Pressure Gauge – is a type of meter used to measure pressure in an airless environment. More specifically, this is a type of meter used to measure the pressure of systems with pressure lower than atmospheric pressure. At that time, the displayed value is shown as a negative number (0), so it is called a negative pressure meter. This type of meter is widely used in pumping systems, air conditioning systems, refrigeration systems, etc. In fact, many people also call it a negative-yang pressure meter. Because like the name suggests, it can measure both the negative measuring range (vacuum pressure) and the positive measuring range. Then, on the watch face there will be two values: negative value (-) and positive value (+).

Normal gauge pressure and vacuum pressure are both measured relative to atmospheric pressure. The difference is that gauge pressure is higher than atmospheric pressure, while vacuum pressure is lower than atmospheric pressure.

Structure and operating principle of negative pressure meter

1. Structure of vacuum manometer

Vacuum manometers have the same structure as other types of manometers, differing only in measuring range. It includes the following basic parts:

• Bourdon tube: Also known as bourdon tube, is the main sensor part (the heart of the pressure meter), which receives pressure from the fluid to be measured and transmits the value to the meter face, usually made of copper material. .
• Socket: Also known as threaded pin, is the connection between the pressure gauge and the device/system.
• Movement: Also known as the transmission, has the function of transmitting the movement of the bourdon tube into the rotation of the clock hands.
• Dial: Also known as the display surface, has the function of displaying the value of measured pressure.
• Pointer: Also called clock pointer, used to display measured pressure value.
• Case: Also known as the watch cover, has the function of protecting the main parts of the pressure watch.
• Window: Also known as the outside protective glass, usually made from plastic or tempered glass.

2. Operating principle of negative pressure gauge

Because the vacuum pressure gauge is a form of mechanical pressure gauge, it has the same operating principle as conventional mechanical pressure gauges: When the medium enters the pressure tube ( also known as bourdon tube), this medium will act on the wall of the bourdon tube, causing the membrane of the tube to expand, affecting the transmission gears and causing the clock hand to move on the scale, displaying pressure value on the display surface.

Types of negative vacuum pressure gauges

Although pressure gauges come in many forms such as bourdon tube, flange, diaphragm, etc., vacuum negative pressure gauges are usually only popular in the regular bourdon tube form. The reason is relatively easy to understand, in applications with a vacuum environment, most of the substances are not special (do not contain many impurities, do not have stickiness, high viscosity, etc.), so they are rarely used. We come across vacuum manometers in the form of flanges, membranes, etc.

Application of negative pressure gauge

Vacuum manometers are used quite widely, because in fact, all industries use vacuum such as automotive, food, beverage, manufacturing, pharmaceutical, chemical, marine, … Vacuum pressure gauges are important devices to ensure optimal system performance and safety.

Note when buying a negative pressure meter

To avoid confusion when choosing, users need to note the following points when choosing a vacuum manometer:

1. Scale

is the thing that users are most likely to confuse when choosing this type of watch. Because in addition to the special scale used to measure the negative pressure range (less than atmospheric pressure) or measure both the negative pressure range and the positive pressure range, the other parameters are the same as other types of copper. Ordinary mechanical watch. Users need to be careful when choosing the right one.

2. Unit of pressure measurement

Each area and each different object will have different units of measurement. Users also need to pay attention when choosing for the right purpose of use, ensuring accuracy and safety for the system. Common vacuum pressure measurement units include: mmHg, mBar, Kg/cm², N/cm², Pa,… In addition to the above two criteria, other criteria are the same as when choosing a conventional mechanical pressure meter. usually, specifically:

• Measuring range (Range): users need to know at least the working pressure of the application, thereby determining the meter’s measuring range. This is necessary, because it directly affects user safety. In case a pressure measuring range is selected lower than the working pressure, overpressure will occur, which can lead to meter destruction and loss of safety. In the case of choosing a pressure measuring range that is too high compared to the working pressure, it is unnecessary, because it will cause inconvenience to the user’s observation due to the large division while the pressure is small, and cause waste. The cost due to the high measuring range is usually higher.
• Diameter of the watch face (Dial): To choose the appropriate watch face diameter, the user must know the installation location of the watch. Large face size makes it easy for users to observe, but has a higher cost and cannot be installed in locations with limited space. Normally, pressure gauges have common diameters of Ø42mm, Ø50mm, Ø63mm, Ø80mm, Ø100mm, Ø150mm, Ø200mm, Ø250mm.
• Connection size: The connection pin is the connection between the watch and the user’s device/system, so the user must choose the type of connection pin to suit their device/system. me. Users must choose the thread type (NPT, BSP,…) thread size accordingly (normally the standard is ½” thread for face size ≥ Ø80mm, ¼” thread for face size Ø50mm Ø63mm, 3/8” thread for face size Ø42mm.
• Connection material: Depending on the working medium, users can choose copper or stainless steel connection material. Copper connection pins have a lower cost and are often used for applications in compressed air systems, steam systems, water systems, etc.
• Included options (Options): users can choose appropriate options based on usage conditions such as damping oil, siphon cooling tube, high temperature applications, additional features external zero adjustment ,…

Makgil specializes in providing genuine negative pressure meters

Makgil Vietnam is one of the most experienced units in the field of supply and installation of pressure and temperature measuring devices, including negative pressure meters. With many years of experience in the industry, Makgil is currently a distributor of ITEC and WIKA brands of EU origin for pressure and temperature measuring devices. With a team of experienced staff, we can also easily advise customers on choosing the type of vacuum pressure gauge that suits their requirements and purposes, with optimal and reasonable costs. most reasonable. In particular, with a very large amount of inventory with a full range of measurements, materials, face sizes, and connection pin sizes, Makgil’s prices are always guaranteed to be the best in the market, with a warranty period of up to 18 months. , ensuring customers can choose with confidence. Customers please note that we do not provide goods originating from China, with Chinese brands, affecting our reputation and the safety of users’ systems. Makgil Vietnam is pleased to serve all customer requests according to the details below: MAKGIL VIETNAM COMPANY LIMITED

• Head office: 18/21 Nguyen Van Dung, Ward 06, Go Vap District, City. Ho Chi Minh
• Hanoi Branch: No. 130 D4 Dai Kim New Urban Area, Dai Kim, Hoang Mai, Hanoi
• Phone: 02866-572-704
• Fax: 02822-026-775
• Website: https://makgil.com Email: info@makgil.com
• Zalo: 0902 949 401 – 0902 988 005 – 0932 798 882