What is the difference between "to contain" and "to deliver" glassware?

Document ID

Document ID TE3672


Version 3.0


Status Published

Published Date

Published Date 09/18/2018
What is the difference between "to contain" and "to deliver" glassware?
"to contain" verses "to deliver" glassware.
Below is from Kimble Kontes® who is the manufature for many of the glassware products offered by Hach.

Proper use of calibrated volumetric glassware requires that the user be informed whether the ware is a “to contain” or “to deliver” vessel. All Kimble calibrated ware is marked either “TC” or “TD”. When the graduation line denotes the volume contained in the calibrated vessel, the ware is marked “TC”. When the graduation line indicates the volume delivered from the vessel, the ware is marked “TD”. When a vessel is calibrated “TD”, it differs from a “TC” calibrated vessel in that a drainage holdback error, the amount of water required to wet the inner surface of the vessel in contact with the water, is added to the “TC” volume. The “TD” vessel then delivers the same volume as contained in a “TC” vessel. Product descriptions in this catalog usually state  the method of calibration used. (The International Standards Organization designation for “to contain” is “IN” and “to deliver”, is “EX”.)

Pipets Calibrated “To Deliver” (EX)
A convenient setup for testing pipets or other instruments ordinarily filled by suction is shown in the Gravimetric Calibration section. The pipet is clamped in a vertical position and the 3-way stopcock connected to it with rubber tubing. The bent arm of the stopcock has a length of rubber hose attached which can be held in the mouth or connected to a vacuum line. Distilled water at the temperature of the room is placed in the large beaker. The water is stirred before use, care being taken not to introduce air into it. Before making a weighing, the pipet is filled one or more times from the beaker by applying suction through the stopcock, in order to bring the pipet to the temperature of the water. Finally the pipet is filled to about 10 mm above the mark, the stopcock closed, and the beaker removed. The stopcock now is opened to connect the pipet to the straight vertical tube and the water lowered slowly to the 0 line. During this emptying, the edge of the tip is kept in contact with the side of the beaker. The rate of descent of the water is controlled by a finger applied to the upper end of this tube. After setting to 0, the stopcock is closed. Then the temperature of the water in the large beaker is taken and this reading is used as the temperature of the water in the pipet. All deliveries should start at the 0 line. To start the delivery into the receiver the stopcock is opened fully, again connecting pipet and vertical tube. The plug is not touched after this, any control needed being exercised by the forefinger on the vertical tube. The same precautions are taken as for burets against splashing of water and
wetting the upper part of the neck of the receiver. Where delivery of a measuring or serological pipet is very rapid, the forefinger must be held on the vertical tube from the start of delivery, but water is retarded as little as possible without losing control. For weighings of intermediate lines, water is allowed to empty until a few mm above the line. Then a finger on the vertical tube is used to slow up the delivery so that the water can be set accurately at the mark. The tip is kept in constant contact with the receiving vessel throughout the delivery. Then the receiver is withdrawn and the stopcock closed. When the pipet has an opaque ring or rings near the top, this indicates that the amount of water remaining in the tip after free delivery has ceased is to be blown out and added to the original delivery. A count of two seconds is made after free delivery has ended and while the neck and tip are still in contact, then air is blown through the rubber hose on the bent arm of the stopcock to eject the liquid in the tip. The neck of the bottle is removed from contact immediately after this. Give only one puff, strong enough to expel the liquid. The time of two seconds has been selected as being the average length of time required in actual service after free delivery has ceased to insert the top of the pipet in the mouth preparatory to blowing through.

Pipets Calibrated “To Contain” (IN)
If the capacity is from a mark to the tip, the pipet should be weighed dry, filled with water to the mark and reweighed. To hold the pipet a saddle may be used on the balance pan. The pipet may be set up as shown in Figure 9 and the filling and setting to the mark accomplished in the same way. Then, a rubber cap or a piece of rubber tubing closed by a short glass rod is slipped up over the tip and the pipet is removed from the stand and weighed. The first weighing of the dry pipet should include the rubber cap or rubber tubing. When the indicated volume is between marks, the pipet is filled completely up to the top mark, weighed, dried and then filled up to bottom mark and weighed. The difference in weight is the apparent weight of the water contained between the two marks. In this case the weight of the empty pipet is not needed.

Flasks and Cylinders Calibrated “To Contain” (IN)
Flasks and cylinders calibrated to contain are cleaned, dried and weighed empty, filled accurately and weighed again. The difference between the two weights, of course, is the apparent weight of the volume contained.

Flasks and Cylinders Calibrated “To Deliver” (EX)
If flasks and cylinders calibrated to deliver are to be calibrated, it will be found best to weigh the filled piece first, empty it and weigh again. The second weight includes the film remaining on the walls after delivery. In all cases, the top of the flask or cylinder should be closed by a cap of some type to minimize evaporation losses. Care must also be taken in handling not to deposit moisture or grease from the hands on the surface of the glass. Therefore, the actual contact with the glass should be by means of a clean cloth, gloves or secure holding device. The entire neck of a flask is wetted by the distilled water and a drainage time of about 2 minutes allowed before completing the setting. To fill a cylinder, the water is allowed to run down one side only, although the entire wall is wetted for about 10 mm above the line to be calibrated by rotation or slightly tipping in several directions. A drainage time of about 2 minutes is allowed before the final adjustment is made. For the final adjustment, a pipet or dropper with a finely drawn point should be used. The temperature of the water can be taken in the filled piece just after the weighing has been completed unless the volume is small. In the latter case, if the thermometer happens to be at a different temperature, the reading obtained may be in error due to the effect of the comparatively large bulk of the thermometer in heating or cooling the water. The alternative is to fill the flask from a reservoir and use the temperature of the water in the reservoir. To calibrate centrifuge tubes, Babcock test bottles and similar articles by weighing the water contained, use the methods outlined for flasks and cylinders, except that the wall is wetted above the line being checked only far enough to insure a correclty shaped meniscus.

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