Can precision scales be operated on batteries? How can they be used in a mobile setting?
If by Precision Scales one means a Laboratory Scale the answer is no, and if one means an Analytical Balance the answer is most definitely no. The lab Scale generally has an accuracy of 0.002% and the Analytical is ten times as accurate at 0.0002%.
These scales cannot maintain their specified accuracy when they are powered by conventional portable batteries where the terminal voltage drifts as the charge level is diminished in the battery. These scales are almost always designed using force substitution magnetic motors in their load cells and they require a sizeable amount of power for normal operation. They are frequently powered by regulated wall transformer type power supplies whose outputs are then regulated again inside the scales. We are talking about loads measured in 100’s of milliamps. This is too great a load for internal portable batteries.
It is easy to determine the volume of any given liquid. All one has to do is put the liquid into a marked container like a graduated cylinder and pour. However, this does not give you an accurate idea of the liquid’s actual weight. For example you could take four graduated cylinders and pour an ounce of safflower oil, Diet Pepsi, tap water and pineapple juice into one of each. Each cylinder will now have an equal amount of the respective liquids in them, but will they weigh the same? No. The weight of the safflower oil will be less, owing to the lower density of the oil.
The Versatile Force Gauge
The Force Gauge is used to measure the amplitude of a force vector at any angle of azimuth and elevation. The Scale used for weighing is special purpose force gauge that is used to measure the force applied to a mass by the earth’s gravitational field, and it measures only at one angle of elevation, namely the vertical axis. Precision scales are capable of making more accurate measurements along the vertical axis as they are carefully aligned using bubble type levels to adjust their legs, and a heavy, but sensitive, magnetic force restoration type of load cell to measure the weight vector
Using Weight to Measure Liquid Volumes for Compounding
It is frequently both more convenient and accurate to measure out the equivalent of a liquid volume using a precision scale rather than a pipette or a measuring cylinder. Most recipes for compounding will call for at least some ingredients to be measured by weight, usually in grams or milligrams. The person doing the compounding, therefore, almost always finds themselves at a workstation which has an accurate scale.
About Moisture Analyzers
The moisture analyzers we are talking about in this article are thermo-gravimetric devices that make the moisture determination by the Loss on Drying (LOD) method. The Karl Fischer Titration technique and others used for the testing of gases are not discussed.
At first glance these LOD systems seem pretty simple. An oven, sitting on top of a scale and a computer (almost always housed inside the Scale) along with its associated software, is used to make the measurements.
On the Importance of Quality in a Precision Scale or Balance
When you are purchasing a measuring device where you expect it to deliver results that are accurate to 0.001% (1 part in 100,000) or 0.0001% (1 part in 1,000,000) and to do so for an extended period of time (like 5 to 10 years), it is wise to invest in a quality device.
Modern high accuracy digital scales are almost all based upon magnetic force restoration load cells. The load cell is the heart of the scale and must be properly designed and assembled of high quality components. How can you, the user, know the quality of the load cell? In truth, you can’t know and must rely mainly upon the reputation of the manufacturer.
Laboratory Balances, Analytical Balances, Semi-Micro Balances, Micro Balances, Why?
Each of the named types (classes) of Balances (Scales) that appear in the title has its proper place the hierarchy of weighing. One thing that they all have in common is that they are high accuracy and high resolution devices designed to do precise weighing in many scientific and industrial applications. Where they differ is mainly in the weight ranges that they are designed to cover and their accuracy.
Selecting Moisture Analyzer Configuration Parameters
Simply stated “It ain’t easy”. However, if we take a somewhat systematic approach it may not be too hard.
Our observations here are intended for Halogen lamp drying systems but apply equally well to IR drying systems. The major difference being that Halogen systems are quite a bit faster because of the broader spectrum of radiation which generates the heat to drive off the moisture. Halogen Moisture Analyzers are far and away the predominant type of units used in both labs and industry. These units generally require the user to select a heating profile, a heating level or gradient, heating cutoff criteria, and a preheat time if a rapid temperature run up mode is selected.
The Difference between a Scale and a Balance
In the past all precision weighing devices were equal arm balances. These devices operated very much in the way that a child's teeter-totter works. Each side of an equal arm balance has a weigh pan on it. The unknown weight was put on one weigh pan and known weights were added to the other pan until the scale came to its equilibrium position, indicating that the known weights added up to equal the unknown weight. Thus, the term “balance” was truly an accurate description for this type of weighing device. It required a set of known accurate weights and the user had to add up the values in order to determine the value of the unknown weight.
Auto calibration … is it worth the investment
One answer to the question could be that it all depends upon the cost. That is true enough, so let's look at the typical cost of the internal auto calibration (IAC) features (we compare identical scales with and without the future). In the 100 g to 500 g capacity range the feature costs approximately $200.
The Moisture Analyzer; Oven over a Computerized Scale
That is a simple observation that covers a wide range of capability.
The first important difference is in the scale used. It may be one of three types; first the lower cost and lower accuracy (approximately 1 part in 3,000) industrial scale based upon strain gauge technology, second the higher cost and higher accuracy (approx. 1 part per 100,000) laboratory scale, and third the highest cost and most accurate (approx. 1 part per 1,000,000) analytical scale. The high accuracy scales do not produce moisture measurements of comparable accuracy as the heating and other factors become large contributors to overall accuracy. Because of this the analytical scale is rarely seen in a moisture analyzer except in research type instruments.
Force Gauge Versatility
The modern digital force gauge is one of the most versatile test and evaluation tools available. This versatility comes through the use of a wide variety of adapters. These adapters range from sophisticated test stands to simple shape adapters. The prices for these adapters cover a wide range as well.