Pressure gauges are essential components of many industrial processes. Pressure measurements are taken to ensure everything is running correctly and efficiently, from monitoring the pressure of a pipeline to ensuring the safety of a manufacturing process. However, without pressure gauge accessories, these instruments can be at risk of damage from the process fluid being measured. This blog will explore the various pressure gauge accessories and how they can help protect a pressure-measuring instrument from potential harm.
Why use Pressure Gauge Accessories?
Pressure gauges and differential pressure instruments are essential for accurately measuring gauge pressure, absolute pressure, or differential pressure. However, these instruments are susceptible to damage caused by the measured process, such as high pressure, extreme temperatures, or pulsating pressure. To help protect against such damage, pressure gauge accessories are available. These accessories can be installed with the gauge to help reduce the likelihood of damage and extend the instrument’s life. Whether you are looking for a protective cover, an isolation valve, or a diaphragm seal, pressure gauge accessories can help ensure the accuracy and reliability of your pressure measurements.
The siphon tube is installed to protect the gauge from high temperatures. Specifically designed for hot vapor applications, these siphons are commonly used in steam systems to reduce the risk of damage to the pressure gauge.
The hot vapor produced by the working fluid is condensed inside the coil of the siphon, preventing the high-temperature vapors from reaching the sensing element of the pressure instrument. The condensed vapor transmits the pressure of the working fluid to the measuring element tube, allowing the instrument to be located some distance away from the actual point of measurement. In steam applications, filling the siphon tube with water during the gauge installation process is common to ensure accurate readings. Using the Siphon, the pressure can be accurately measured without needing to be located directly at the point of measurement.
There are two common forms of the siphon tube – the “U” and the ring type, also known as the pigtail. Which one you choose depends on the orientation and available space of the pipes. The “U” is often used for horizontal pipes, while the ring type is better suited for vertical and tight spaces.
The ring tube is best used on horizontal pipelines when adequate space is above the pipe. For vertical pipelines or horizontal pipelines with limited space, the ‘U’ type Pressure Gauge Siphon is the ideal choice. This Siphon offers the same excellent performance as the ring tube while allowing for easier installation in tighter spaces.
A snubber is a device that helps to reduce pressure pulses and fluctuations caused by reciprocating pumps and compressors, creating a smoother and more accurate pressure indication and extending the life of the gauge. Furthermore, a snubber can increase the time between calibrations, providing greater accuracy and a longer-lasting gauge.
Another method of reducing pulsations is to use a glycerine-filled gauge. The liquid-filled gauge acts as a shock absorber, effectively smoothing out vibrations by absorbing the pressure spikes in the system. Glycerine-filled gauges are generally more expensive than snubbers but offer superior performance in dampening pulsations.
Three types of snubbers are available for different applications: porous, piston, and throttling snubbers. Porous snubbers are great for general usage, and piston snubbers usually come with two or more pistons for versatility. Throttling snubbers have a built-in needle valve or variable orifice that can be adjusted externally, and for added safety, an anti-blow-out stem is recommended. No matter the application, choosing the right snubber to protect your system is essential.
3. Overpressure Protector
An overpressure protector is an essential safety device to protect a pressure gauge from exceeding its maximum pressure rating. It’s designed to prevent damage to internal components, loss of calibration, or even the rupture of the sensing element. When the preset pressure is reached, the protector will shut off the pressure to the gauge and reset when the pressure drops by at least 10% (varies by manufacturer).
For added convenience, it’s usually best to purchase an overpressure protector when buying a new pressure gauge. The protector is usually factory set to 1.1 x the maximum scale value of the gauge. This provides an extra layer of protection, allowing gauges with different pressure ranges to be installed in ascending stages and enabling even low ranges to be read accurately when the total range is much higher.
4. Gauge Adapter
A gauge adaptor is a must-have for any process plant operator, allowing them to orient the dial face of a pressure gauge in any direction through 360°. This ensures that the gauge is always easily visible, making monitoring and controlling the process easier. Additionally, some manufacturers provide gauge adapters with male threads of different sizes from the female threads of the connected parts, making it easier to design the gauge hook-up.
5. Gauge Saver
The gauge saver is ideal for safeguarding your pressure instruments when the process pressure exceeds the over-range limit. When the preset pressure is exceeded, the gauge saver cuts off the pressure on the instrument, protecting the sensing element and preserving its accuracy and calibration. With the Gauge Saver, you can be sure that your pressure instrument will remain safely operational and accurate for years to come.
6. Gauge Union
The gauge union makes instrument installation more manageable by providing the flexibility to position the instrument at the optimal angle. It is available in various materials such as SS304, SS316, and Monel and is designed to be durable and long-lasting. With its easy-to-use design, the Gauge Union or Universal Adaptor (Swivel Adaptor) makes instrument installation simple and efficient.