HM Digital Manufactures Water Quality Testing Equipment

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HM Digital manufactures water quality testing equipment, including tests for pool salt and pH test strips. Watermaid Canada also carries HM Digitals total solids water testing equipment.

Established in 1987, HM Digital, Inc is an original equipment manufacturer that has been recognized worldwide for providing the best values in water testing instrumentation, especially the increasingly popular TDS meter.

Of all the buzzwords that are swimming around the world of water quality these days, "TDS" is one of the most common. Given that TDS is by far the most common parameter for water quality testing, an overview of the subject is warranted. TDS is anything-other than the pure H2O-in water that you cannot see. This could include any salt, metal or mineral, and the lower the TDS level is, the purer the water. So then why should TDS be measured? As an overall indicator of water purity, TDS is an especially important parameter, and more often than not, it is the first one tested. A TDS test is quick, easy and inexpensive. A single TDS meter can be used thousands of times, requiring nothing more than the occasional recalibration and new batteries. Choosing the right device for a system is of utmost importance.

Handheld meters

The biggest advantage of a handheld meter is its portability and versatility. You can use a handheld meter not only in your own home for the Reverse Osmosis system, but for a variety of water sources and even on that family trip to Cancun.

The majority of handheld meters on the market have wide ranges, such as 0-9,999 parts per million (ppm); long-lasting batteries; and in some cases a color-coded chart illustrating TDS values. They are simple to use with a push of a button. A handheld meter is usually the least expensive way to go.

Limits of handhelds

Handheld meters have their limitations, since they are easy to lose or you may not want to take the time to use it.

In-line monitors The advantage of an inline monitor is its ease of use. The majority of inline monitors are simple to turn on with the push of a button, possibly followed by a flip of a switch to obtain both the readings of the feedwater and the product water.

Monitors are typically battery-powered and attached directly to the Reverse Osmosis system. A Reverse Osmosis system works by using pressure to force a solution through a membrane, retaining the solute on one side and allowing the pure solvent to pass to the other side.

Multi-stage monitoring

For example, the first sensor could be connected after a carbon filter and the second sensor could be connected after the membrane. When used in conjunction with a handheld meter to determine the tap water TDS value, this could be an effective setup for determining which stage of the RO system needs servicing. Similarly one could install two or even three monitors for systems with more stages. The primary disadvantage of an inline monitor is the installation requirement. However, with a quick-connect T-fitting, this can be done quite simply. Inline monitors are more expensive than handheld units, and since all monitors currently on the market only monitor a maximum of two lines, a multiple-monitor configuration could involve some expense.

Large-scale control

Controllers are ideal for industrial or large commercial RO systems.

Besides monitoring TDS continuously, controllers also have a set-point. When the TDS levels rise above this pre-programmed level, the controller will perform an action, such as sounding an alarm; turning on a flashing light; or sending an signal to a control station.

Controllers are always AC-powered, so viewing TDS levels is as simple as taking a look. Controllers are typically more accurate, with better sensors, and can control one or two lines.

The biggest disadvantage of a controller is the price. At the very least, a controller will be five times the price of a monitor and ten times or more the price of a handheld unit, which is why they should only be installed on a need basis.

Monitoring TDS levels is virtually essential for any RO system, and can often be done at nominal cost.