You may think all you've got to do to read a syringe is […]
You may think all you've got to do to read a syringe is look at the lines on the tube. But different syringes measure volume in different increments, and sometimes they don't use the standard unit, milliliters (mL). This can make the process more difficult than it looks! Always start by double-checking your syringe's unit of measurement, and the value of each line on the tube. To get an accurate measurement, all you need to do is fill the syringe and push the plunger down to the amount you need to measure out.
Measuring by a Syringe's Marks
Check the units of your syringe. There are many different sizes of syringes. Most will be clearly marked in milliliters (mL). You'll see hash marks on the tube of the syringe. Each 1 marks a certain number of milliliters or fractions of milliliters.
Some syringes, such as those used to measure insulin, are marked in numbers of "units" rather than milliliters.
Some older or non-standard syringes may also use different units.
Count the lines on a syringe marked in even-numbered increments. Most syringes include incremental hash marks between larger, numbered ones. For instance, you might have a syringe that is marked large lines at 2 milliliters (0.068 fl oz), 4 mL, and 6 mL. Halfway between each of these large lines, you might see a slightly smaller line. In between each numbered line and the slightly smaller line, you would then see 4 even smaller lines.
Each of the smallest lines would count for 0.2 milliliters (0.007 fl oz). For instance, the first line above the 2 milliliters (0.068 fl oz) line would equal 2.2 milliliters (0.068 fl oz), the second line above it would equal 2.4 mL.
The mid-sized line halfway between each number would equal the odd number in between. For example, the halfway mark between 2 milliliters (0.068 fl oz) and 4 mL equals 3 mL, and the mark halfway between 4 milliliters (0.14 fl oz) and 6 mL equals 5 mL.
Read a syringe marked in consecutive increments. For instance, your syringe may be marked with a number at every successive mL. In between you'll see a mid-sized line that marks half mL units, like 0.5 milliliters (0.02 fl oz), 1.5 mL, 2.5 mL, and so on. The 4 smaller lines between every half mL and mL line each mark 0.1 mL.
So, if you need to measure 2.3 milliliters (0.08 fl oz), draw the liquid to the third line above the 2 line. If you need to measure 2.7 milliliters (0.09 fl oz), that will be the second line above the 2.5 mL mark.
Your syringe may be marked in other increments, such as multiples of 5 milliliters (0.17 fl oz) or in fractions of 1 milliliter (0.034 fl oz). If so, the principle stays the same—just look for the major numbers marked on the syringe, and count the smaller marks in between.
Measure in between the hash marks, if necessary. Sometimes you will be asked to measure an amount that is not exactly marked by the hash lines on your syringe. To do this, you'll have to count between the lines.
For instance, say you have been asked to measure 3.3 milliliters (0.1 fl oz) of a medication, but your syringe Is marked in hash marks of 0.2 milliliters (0.007 fl oz) increments.
Pull the medication up the syringe and then push the plunger down until the medication is between the 3.2 milliliters (0.1 fl oz) and 3.4 mL lines.