Editor's Choice


SA Gauge: A shining example of South African resilience

November 2022 Editor's Choice

Chris and Judith du Plessis founded SA Gauge with a fairly modest vision, but one that was vivid and focused enough to lay the groundwork for a proudly South African company that has stood the test of time. Celebrating its 30th birthday this year, the company’s welcome return to the first post-COVID-19 Electra Mining Africa was somewhat bittersweet, as it marked its first showing at the event without its spearhead in attendance.

Chris du Plessis passed away on 12 January 2021 at the age of 61, but his legacy is an SA Gauge that is barely recognisable from the original, back when he and his wife used to stay up at night making gauge scale plates by hand. Armed only with the idea of manufacturing pressure gauges and thermometers locally, a can-do attitude and six staff members, the Du Plessis couple steadily grew the business to encompass two self-owned branches and two SANAS-approved laboratories, one for pressure and the other for temperature.

Through thick and thin

As with any business, SA Gauge has had its ups and downs over the years, and relocations to accommodate its growing market share and number of personnel. Since its inception in 1992 as one of only two local manufacturers of branded pressure gauges and thermometers, many milestones have followed.

The company’s first branch was in Germiston, where Chris and his family lived at the time, and when they moved to Durban in December 1995, a second branch was opened there which became its new head office. Initially located at 9 Beechfield Crescent in rented 250 m2 premises, the headquarters moved directly across the road for a spell before SA Gauge bought its own property in 2007. There have been no more moves since, and SA Gauge is based at 8 Beechfield Crescent in Springfield Park, Durban to this day. In 2011 the Johannesburg branch also moved from Germiston to a larger, self-owned factory in Croydon, Kempton Park on the East Rand of Johannesburg.

In 2008 the company opened its first SANAS-accredited lab, in Durban, specifically for the pressure gauge side of its business. As the SA Gauge team puts it, “the places we move into always seem so big when we move in but within a few years we manage to outgrow them.” A second lab, this one for its temperature gauge business, was opened in Croydon in February 2019 before moving to Durban in March 2020.

As was the case for almost everyone, COVID-19 was a trying time for the staff as fears of job losses escalated. Fortunately, Chris and Judith always believed in being prepared for a rainy day and were able to pay all their employees in full for the entirety of the lockdown, and no jobs were lost. Very unfortunately, the company suffered the double-whammy of losing two team members in January 2021: Chris and Dinesh Betchan, technical salesperson and SANAS laboratory manager.

Emerging stronger than ever

Now, backed by a complement of more than 50 staff members and having managed to meet sales targets since lockdown, and in some cases far exceeding them, SA Gauge is back in growth mode. It recently completed the construction of an additional 100 m2 factory floorspace to allow for a new press and lathes, into which it will be moving two sections of its manufacturing operations. A new SANAS lab is also being built and is expected to be up and running in January 2023. At 145 m2, it will be a fair bit bigger than the current lab to accommodate more equipment and improve turnaround times.

A major headache the company is dealing with right now is the unstable electricity supply, which necessitated an investment in generators to keep its systems up and running. In future, it plans to investigate the addition of solar power systems to keep critical systems online all the time.

The future, though, looks bright for SA Gauge as it continues to draw from the principles instilled by Chris du Plessis. “Chris was very big on being prepared and trying to make sure that whatever was thrown at us, we could find a way around it or over it. Loyal staff members also makes things much easier. Everyone pulls their weight and helps out when needed, without management having to ask. If SA Gauge fails, we all fail. We have managed to create a range of products that is of a superior quality and marketed at competitive pricing,” reads a joint message from the team.

Technical advice for industry

SA Gauge is about more than just pushing product, as it strives to not only satisfy its customers, but also educate them to make the best possible use of their pressure and temperature gauges. In that spirit, the company offers the following tips for end users to bear in mind.

Accuracy class

This helps to determine whether or not the unit under test (ie, the customer’s gauge) is within its specification. Master gauges boast a high accuracy: often around 0,5% or 0,3% of full-scale for analog models, while digital gauges can range all the way from 1% to 0,01%. In order to know if your item is within specification, simply take the full range and multiply it by the accuracy percentage of their item.

Pressure media

For lower-pressure gauges, air is most commonly used, but other gases like nitrogen can also be used. With higher pressure ranges, liquid media such as water or oil are more common. Oxygen gauges need to be degreased to ensure that there are no common contaminants, such as water or oil, that can get into the gauges and cause an explosion.

Generating pressure

Oftentimes the company sees pressure gauges coming in that have been over-pressured due to an unseen spike in the customer’s system, usually upon startup. This spike can occur very quickly, but it is often too quick and too high a pressure for the mechanical gauge to endure. When this happens, a snubber can be fitted to the gauge to prevent it from happening again.

Hysteresis

Hysteresis occurs when there is a difference in the pressure point reading when the pressure is increased and then decreased again. To find out the hysteresis of the gauge, it should be calibrated first with increasing pressure only, and then again with decreasing pressure. Both readings should be recorded.

‘Tapping’ the gauge

Due to analog pressure gauges being mechanical in nature, ‘tapping’ is often needed. This occurs when the desired calibration point has been achieved and the calibrator gently taps the side of the gauge to correct any mechanical ‘lag’ or stickiness. This ensures a truer reading of the value.

Adjustment/correction

Mechanical gauges often drift over time. When this happens, the internal components can be adjusted to bring the item back into its specified accuracy class. Adjustments can also be made on gauges that have been bumped or dropped, where the gears may have shifted as a result.

Calibration certificates

Calibration certificates are critical pieces of documentation, since they show the unit’s history in addition to pertinent information such as the calibration lab’s company details, the unit’s accuracy and the error calculation.

Order the right gauge for your application

There are several things customers of SA Gauge either get wrong, or fail to consider, when ordering a gauge. To ensure that what you buy is exactly what you expect, take note of these key points:

• Provide the correct information about the gauge you require – dial size, fitting size, bottom or rear entry, etc.

• Specify the correct unit of measurement, such as kPa or MPa versus bar in the case of a pressure gauge.

• Understand the application the gauge will be used in. Failure to do so can lead to ordering standard pressure gauges instead of diaphragm seal gauges, or glycerine-filled gauges for oxygen applications.

• Do not assume that all new gauges come with calibration certificates; SA Gauge clearly specifies that this is an optional extra.

• Do not order the incorrect calibration certificate under the assumption that the SA Gauge calibration will be sufficient for ISO auditing purposes.

• When ordering thermometers, specify the correct probe length – for the most part, specifications from SA Gauge include the thread length.

• For tonnage gauges or kN gauges, choose the correct ram sizes of the press and hand pumps. This is crucial, as it could lead to people being injured if incorrect pressure ratings are used to manufacture the gauge.


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