Blog posts of '2016' 'December'

A pressure gauge out of calibration can be extremely frustrating.  The gauge may constantly point off of zero when there’s no pressure in the line or the gauge is consistently reading 5% above or below the range it really should be reading based on your other instrumentation.

One solution to this problem is to utilize the adjustable pointer on the pressure gauge assuming your gauge has one.

Most industrial pressure gauges will have an adjustable pointer because gauges will commonly fall out of calibration out in the field due to vibration, pulses, or just general use.  Gauges that don’t typically have them are smaller utility pressure gauges or liquid filled gauges.  Usually they’re lower in cost and its cheaper just to replace than try and worry about adjustments.

Below is a link to a video by our friends at Kodiak Controls explaining how to adjust the calibration of a pressure gauge using an adjustable pointer.  Keep in mind that an adjustable pointer can only help if the needle is off by 1-10% of the full range.  So, if you have a 100 psi gauge and the needle is always off by 3 psi, an adjustable pointer will work great.  But, if your 100 psi gauge is off by 30 psi, an adjustable pointer is not your solution.  There is a bigger issue at hand and you may need to purchase a new pressure gauge.  Enjoy the video!

How to Use an Adjustable Pointer

Digital pressure gauges have been around for decades, but until recently, they have become more relevant in industrial, laboratories, and testing applications than ever before.   So, why the change?
Here are a few reasons why digital pressure gauge usage has surged.
1.) Cost – The cost of digital gauges has dropped dramatically over the last 5-7 years.  In the past, one might expect to pay around $300-$400 for a standard digital gauge with basic features.  At that price, it didn’t really merit switching from mechanical gauges that could be purchased around $20.  However, now due to technology and more efficient production, digital gauges can be purchased as low as $125 for high accuracy units or as a low as $15 for a real basic digital gauge.
2.) Availability – With costs being lower and usage going up, many digital gauges are being stocked in standard configurations instead of being made-to-order.  This allows customers to have easier access and quicker deliveries on these products.
3.) Point-of-Reference Display – Its much easier to get an accurate reading by looking at a digital display instead of an analog dial.  Think about looking at a mechanical clock vs. a digital clock.  The reading is clear and concise.  There is no “fudge factor” in the reading.
4.) Special Features – Digital pressure gauges can also come with additional features like:

•  4/20mA outputs
• numerous scale readings
• max and min readings
• data logging
• no moving parts = more durability than mechanical gauges

5.) They’re Better  – Digital pressure gauges are overall just flat out better than mechanical gauges.  They’re more accurate in most cases, readings are easier to get, 4/20mA outputs are available, and digital gauges are more durable.
One thing is for sure, digital gauges aren’t going anywhere anytime soon.
For more information on digital gauges, visit our digital pressure gauge page or contact us.

At Big Bear Instruments, we're strive to provide great products at great prices. One of the products we'd like to highlight this week is a mini digital pressure gauge manufactured by Kodiak Controls.
Kodiak’s new KCDG15 digital gauge is perfect for reading pneumatic pressure applications where higher accuracy, better durability, and clearer readability is needed over a standard analog mechanical pressure gauge.  The KCDG15 digital gauge is designed to be a better overall pressure gauge and provide a more reliable reading while still keeping the price much lower than a traditional digital gauge.
The KCDG15 is battery operated and can come in 1/8″ npt or 1/4″ npt threaded connections (other options available at request) and is 0-145 psi standard (other ranges also available).  It is battery operated and has a 1.0% F.S. accuracy with LCD display.
For additional details or to purchase this mini digital gauge, check out the product page.

On high vibration industrial applications, reading a pressure gauge can often be frustrating or in some cases down right impossible without the proper configuration on the gauge.  Very often, the end user may experience:

• The indicating needle shaking back forth making it difficult to get an actual reading
• The indicating falling off its access from the vibration
• Damage or short longevity of the gauge due to constant wear and tear of the pressure gauge internals

There are a few options that can be used to help legibility of the pressure gauge:

1. Liquid Filling – Liquid filling the gauge with either a glycerin or silicone is easily the most popular solution and least expensive.  The viscosity of glycerin or silicone makes it a thicker fluid than something water.  With the case filled with glycerin, the needle has a harder time from shaking back forth from the vibration.  This in turn steadies the needle and allows for accurate reading.  In addition to help steady the needle, the glycerin also acts as a lubricant for the internals of the pressure gauge allowing for a longer life out in the field.
2. Dampening Movement – Getting a pressure gauge with a dampening movement is the next best option especially for those who do not like liquid filling and prefer a dry gauge.  A silicone dampener is put on the internals of the pressure gauge near the axis of the pointer.  This steadies the pointer and allows for the same outcome as if the gauge was liquid filled.  Typically a dampening movement needs to be special requested though
3. Capillary Tubing with Diaphragm Seal – As an option for extreme vibrating applications where liquid filling and/or dampening movements aren’t enough, the pressure gauge is often mounted to a capillary tube and diaphragm seal filled system.  The diaphragm seal is mounted at the process connection.  Capillary tubing (often 5 feet in length) is connected to the diaphragm seal and on the other end of the tubing is the pressure gauge.  The pressure gauge is then typically mounted to a wall or panel away from the vibration and a proper reading can be seen.  The diaphragm seal, capillary, and gauge assembly is filled with a fluid (often silicone), to allow for an accurate reading.

For a complete list of our liquid filled gauge options, take a look at our mechanical gauges product page.

For differential pressure applications with caustic or thick medias, mounting a differential pressure gauge directly to the process can be detrimental to the integrity of the gauge.  The wetted material of the gauge may corrode away or the differential gauge could potentially become clogged.

A solution to this problem would be to isolate the wetted parts of a differential gauge by mounting diaphragm seals made of a compatible metal or plastic to the inlet and outlet sides of the differential gauge.  However, unlike a standard pressure gauge with one port, you cannot mount a diaphragm seal directly to the differential gauge because the ports of the gauge are typically too close together to accommodate the size of the diaphragm seal.

A solution to this is to install capillary tubing in between the gauge and the diaphragm seal.  This allows for flexibility during installation, safety from high temperatures or vibration, and room for the diaphragm seals to fit on the gauge.  The entire assembly is a filled system just like a standard gauge mounted on a diaphragm seal.  The air is evacuated from the assembly and replaced with a fluid (usually silicone or glycerin).
For more information on differential gauges and/or mounting instruments to diaphragm seals, contact us.

A pressure instrument by itself typically has a small orifice for the media to enter into it for measurement.  This works perfectly fine for applications such as water, air, or oil measurements.  But what do you do if the media has solids in it, is thick, and/or solidifies when it cools that can potentially clog the pressure instrument rendering it useless?
The answer is mount a diaphragm seal to the instruments.  A diaphragm seal is specifically designed to be a barrier between the media and the pressure instrument.  Pressure gauges, pressure transducers, and pressure switches can all be mounted to diaphragm seals (or gauge isolators as they’re sometimes called) through a “filling process” creating a sealed system between the instrument and the seal allowing for the utmost accuracy.
There are many kinds of diaphragm seals and all are used based on what fits best for the application.  Some types include:

• Mini Diaphragm Seals
• Large Diaphragm Seals
• Plastic Diaphragm Seals
• Flow-Through Diaphragm Seals

IMPORTANT: You cannot simply screw on a diaphragm seal to a pressure instrument.  As mentioned above, it needs to be a filled system.  Essentially the instrument is mounted to the diaphragm seal.  Then air is evacuated from inside the connection and replaced with a fill fluid such as glycerin, mineral oil, or silicone.  This allows for an accurate reading.
For more information on diaphragm seals or the mounting process, please contact us.