Ancillary equipment in laboratory practice

G.Patton

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Introduction.

Laboratory Equipment — Various instruments and equipment used by laboratory personnel to perform experiments or measurements. Laboratory equipment is subdivided into general laboratory equipment, measuring equipment, specialized equipment, testing equipment, and analytical equipment. In this topic, we will consider additionally laboratory equipment, which is no less important than laboratory glassware.

Most common equipment:

Retort stand.
In chemistry, a retort stand, also called a clamp stand, a ring stand, or a support stand, is a piece of scientific equipment intended to support other pieces of equipment and glassware — for instance, burettes, test tubes and flasks. The typical retort stand consists of a heavy base and a vertical rod, both usually made of metal. A number of accessories, such as clamps of various types and iron rings, can be attached to the rod by thumbscrews, at whatever heights and orientations are necessary to support the target equipment.
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Ring stands, rings, and clamps: Ring stands are used to suspend beakers, flasks, etc., usually above a heat source. Clamps are used to ensure a firm grip on the containers.

Clamps for securing apparatuses.

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Item Name:
  1. Extension clamps (with and without vinyl sleeves).
  2. Three-fingered clamps (vinyl and fire-resistant sleeves).
  3. Ring clamp (iron rings).
  4. Wire mesh.
A clamp holder or clamp fastener is a piece of laboratory apparatus that is used to secure laboratory clamps, such as extension-type utility clamps, or other attachments to a ring stand or lab frame. The material can be made up of brass, cast iron, stainless steel, aluminium or nickel-plated zinc.

An iron ring or ring clamp is an item of laboratory equipment which comprises a conjoined metal ring and radially extending rod. In some cases, the rod terminates in a screw clamp for attachment to a retort stand or other support; in others, the rod may be attached to a stand by means of a laboratory clamp holder. Iron rings are commonly used in chemistry laboratories for supporting apparatus above the work surface, for example:
  • A tapered item such as a filter funnel or separatory funnel.
  • A clay triangle, which itself supports an item such as a crucible.
  • A wire gauze, which itself supports a flat-bottomed beaker or conical flask.
  • A large and therefore heavy, round-bottom flask.
In some cases, a slot is cut in the side of the ring opposite the rod. This is to allow a funnel to be placed upon and removed from the ring from the side rather than from above, a safer procedure.

Wire gauze.

A wire gauze is a sheet of thin metal that has net-like patterns or a wire mesh. Wire gauze is placed on the support ring that is attached to the retort stand between the Bunsen burner and the glassware to support the beakers, flasks, or other glassware during heating. Wire gauze is an important piece of supporting equipment in a laboratory as glassware cannot be heated directly with the flame of a Bunsen burner, and requires the use of a wire gauze to diffuse the heat, helping to protect the glassware. Glassware has to be flat-bottomed to stay on the wire gauze.
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Burners.

Alcohol burner.
An alcohol burner or spirit lamp is a piece of laboratory equipment used to produce an open flame. It can be made from brass, glass, stainless steel or aluminium. Alcohol burners are preferred for some uses over Bunsen burners for safety purposes, and in laboratories where natural gas is not available. Their flame is limited to approximately 5 centimeters (two inches) in height, with a comparatively lower temperature than the gas flame of the Bunsen burner.
Some wire gauze has a ceramic center. Plain wire gauze can transmit heat efficiently, but gauze with a ceramic center will also allow the heat to be dispersed more evenly. The ceramic at the center of the wire gauze is enmeshed at high pressure to prevent it from peeling.
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Bunsen burner.
A Bunsen burner, named after Robert Bunsen, is a kind of gas burner used as laboratory equipment; it produces a single open gas flame, and is used for heating, sterilization, and combustion. The gas can be natural gas (which is mainly methane) or a liquefied petroleum gas, such as propane, butane, or a mixture. Combustion temperature achieved depends in part on the adiabatic flame temperature of the chosen fuel mixture. Maximum temperature of flame can reach 1560 °C.
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Heating mantle.

A heating mantle, or isomantle, is a piece of laboratory equipment used to apply heat to containers, as an alternative to other forms of heated bath. In contrast to other heating devices, such as hotplates or Bunsen burners, glassware containers may be placed in direct contact with the heating mantle without substantially increasing the risk of the glassware shattering because the heating element of a heating mantle is insulated from the container to prevent excessive temperature gradients. Heating mantles may have various forms. In a common arrangement, electric wires are embedded within a strip of fabric that can be wrapped around a flask. The current supplied to the device, and hence the temperature achieved, is regulated by a rheostat. This type of heating mantle is quite useful for maintaining an intended temperature within a separatory funnel, for example, after the contents of a reaction have been removed from a primary heat source.

Another variety of heating mantle may resemble a paint can and is constructed as a "basket" within a cylindrical canister (often made of plastic or metal, such as aluminium). The rigid metal exterior supports a "basket" made of fabric and includes heating elements within the body of the heating mantle. To heat an object, it is placed within the basket of the heating mantle.

In further contrast to other methods of applying heat to a flask, such as an oil bath or water bath, using a heating mantle generates no liquid residue to drip off the flask. Also, heating mantles generally distribute heat evenly over the surface of the flask and exhibit less tendency to generate harmful hotspots.
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Laboratory thermometers.

Laboratory thermometers are devices used to measure temperature. There are many types of lab thermometers such as differential, mechanical, logging, etc. Laboratory thermometers are progressively providing digital reading displays and are input-capable to computer and software programs for logging purposes. A laboratory thermometer can be used for a number of scientific applications and can be found across nearly all laboratories, especially in pharmaceutical, environmental, food, and petroleum testing. While a lab thermometer can measure how hot or cold a sample or environment is, the range of measurement can vary widely between models.

Precise thermometric testing and recording of a given sample – or determining ambient temperature and humidity – is often an integral part of accurate materials testing. So is determining which type of field/lab thermometer best matches your specific materials testing needs. This blog post helps take the heat out of the process and offers insight into Liquid in Glass (LiG) mercury thermometers, non-mercury LiG thermometers, and digital thermometers. It also provides information surrounding restrictions of mercury LiG thermometers, including in laboratory and industrial uses, and finally, considerations for determining which type of thermometer meets your needs.

ASTM Mercury Thermometers for Materials Testing
Once one of the most common of LiG thermometers, mercury thermometers were touted for their high level of accuracy and ability to measure extreme temperature ranges. For at least the past two decades, however, numerous state, local and federal agencies have classified mercury as toxic, with many phasing out and banning the use of mercury in thermometers and other devices. Sales and shipping of mercury instruments are often regulated and sometimes prohibited by a given locale as well. The National Institute of Standards and Technology (NIST) stopped calibrating mercury thermometers in 2011, and non-mercury alternatives began to grow in utilization and technological advances.
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Tubes and hoses.

In various types of facilities for equipping laboratories, when connecting inlet or outlet pipelines made of metal and plastic, flexible pipes made of rubber, polyethylene, silicone, polyvinyl chloride are used. Laboratory tube, can serve as a continuation of glass bends. For example, it can be put on the outlet valve of an electric laboratory distiller to direct the distillate into prepared glassware, put on the outlet of the refrigerator, transfer pump or funnel.

Requirements for laboratory hoses:
  • Resistant to chemicals. That is why the tubes are made of neutral materials that do not interact with overflowing, pumped liquids. Although this cannot be avoided completely.
  • High-temperature resistant. Elastic tubing should not crack or soften excessively.
  • Flexibility. They cannot be bent at a right and even more acute angle, since this laboratory accessory has a “memory”; after a sharp bend, it will not return to its original shape and most likely you will have to buy a new one.
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Item Name:
  1. Thick-walled vacuum tubing.
  2. Bunsen burner.
  3. Wood blocks.
  4. Rubber tubing.
Tube classification:
  • Outside and inside diameter. In turn, this indicator determines the maximum viscosity of the solutions that pass inside the tube. The smaller diameter and the higher density of the liquid, the more likely it is that movement will simply stop due to blockage in the cross-section. Similar happens with an anchor of a magnetic stirrer, which can get stuck in a viscous mass;
  • Tube classification:
  • Outside and inside diameter. In turn, this indicator determines the maximum viscosity of the solutions that pass inside the tube. The smaller diameter and the higher density of the liquid, the more likely it is that movement will simply stop due to blockage in the cross-section. Similar happens with an anchor of a magnetic stirrer, which can get stuck in a viscous mass;
  • By wall thickness. Thick-walled tubing, especially fiber-reinforced, is used for pumping gases and liquids at high pressures. In this case, special attention should be paid to the tightness of the docking joints, where a flexible hose or laboratory branch pipe is connected to an outlet, tap, outlet.
  • By the quality of rubber, silicone and other material. You should pay attention to 2 aspects. First, caustic reagents, organic solvents, alkalis, acids, aggressive gaseous components can interact with the inner surface of the tube, destroying it. Secondly, the purity of a chemical experiment can be violated, when, for example, compounds penetrate from a rubber tube into a solution, acting as a contaminant.

Tools used in all laboratories.

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Tools used in all chemistry courses:
Item Name:

  1. Crucible tongs.
  2. Test tube holder.
  3. Striker.
  4. Forceps.
  5. Spatulas.
  6. Scoopula.
  7. Glass stirring rod.
  8. Pasteur pipette.
  9. Dropper bulb.
Tongs and forceps are used to handle, hold and grab containers of different kinds. Tongs can hold wider tubes, while forceps usually work on smaller containers like graduated cylinders and test tubes.
Spatulas and scoopulas are used to scoop out chemicals and solids out of containers and onto a crucible for weighing. They are also sometimes used to mix chemicals.

Wash bottles.

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A wash bottle is a squeeze bottle with a nozzle, used to rinse various pieces of laboratory glassware, such as test tubes and round bottom flasks.
Wash bottles are sealed with a screw-top lid. When hand pressure is applied to the bottle, the liquid inside becomes pressurized and is forced out of the nozzle into a narrow stream of liquid. The use of wash bottles helps researchers control and measure the precise amount of liquid used. In addition, unwanted substances or particles cannot pass through wash bottles. The use of wash bottles is more convenient than using beaker and graduated cylinders.

Rubber fitting for thermometer adapter.

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Used to install a thermometer in the neck of the Kleizin joint or anyone else. It allows keeping joint isolated from atmosphere.

Plastic clip (Keck clip).

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Keck clips are special-purpose clips: they hold two pieces of standard taper glassware together. They are made of plastic and will melt if they get too hot, and they break easily without any provocation.

Clamping.

Organic chemistry glassware is often segmented so that pieces can be arranged in a variety of ways to create setups that achieve different goals. It is important that the pieces are securely fastened in an apparatus so that flammable vapors don't escape and pieces don't fall (whereupon the glassware may break or contents may be spilled). Some chemistry labs have a lattice-work of metal bars (Fig.1 c) secured to the bench top that can be used for clamping apparatuses, and other labs rely on ring stands (Fig.1 a). Ring stands should be positioned so that the apparatus is clamped directly over the heavy metal base, not in the opposite direction as the base (Fig.1 a, not Fig.1 b).
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a) Correct clamping of an apparatus to a ring stands, with the apparatus directly over the metal base, b) Incorrect use of a ring stand, where the apparatus is not directly over the metal base, c) Metal lattice-work for clamping apparatuses.
Metal clamps are used to connect glassware to ring stands or the metal lattice work. Two common types of clamps are "extension clamps" and "three-fingered clamps" (Fig.2 a). Although in many situations the clamps can be used interchangeably, an extension clamp must be used when clamping to a round bottomed flask (Fig.2 b), as 3-fingered clamps do not hold well. The extension clamp should securely grasp the neck of a round bottomed flask below the glass protrusion (Fig.2 b, not Fig.2 c). Three-fingered clamps are generally used to hold condensers (Fig.1 b), suction flasks, and chromatography columns (Fig.3).
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a) Extension and three-fingered clamps, b) Correct use of an extension clamp on a round bottomed flask, c) Incorrect clamping (flask may slip).

Both types of clamps often come with vinyl sleeves that may be removed if desired. The vinyl sleeves provide a gentle grasp for glassware, but should not be used with hot pieces as they may melt (or in the author's experience catch on fire!). Sometimes fire-resistant sleeves are also provided with clamps as an alternative (right-most clamp in Fig. 2 a).
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a) Flasks, b) Chromatography columns, c) Pipette columns.

Ring clamps (or iron rings) are also commonly used in the organic lab. They are used holding separatory funnels (Fig. 4 a), and can be used to secure funnels when filtering or pouring liquids into narrow joints (Fig. 4 b). Furthermore, they can be used along with a wire mesh to serve as a platform for supporting flasks (Fig. 4 c).
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a) Holding separatory funnels, b) Holding funnels, c) Assembly of an adjustable platform.

Plastic clips (sometimes called "Keck clips" or "Keck clamps") are also commonly used to secure the connections between joints (Fig. 5). The clips are directional, and if they don't easily snap on, they are probably upside-down. Plastic clips should not be used on any part of an apparatus that will get hot, as they may melt at temperatures above 140 ˚C (Fig. 5 b). Metal versions of these clips can be used alternatively in hot areas. Clips should not be relied upon to hold any substantial weight, as they can easily fail (especially if they have been warmed). Therefore, reaction flasks should not be held with just clips, but always supported in some more significant way (e.g. with an extension clamp attached to a ring stand).
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a) Using a plastic clip, b) Melted clip

Conclusion.

I've described most common laboratory equipment which wasn't mentioned in Laboratory glassware theme. Hope this information will be useful and helpful for all visitors of our forum. If you have questions, do not hesitate to contact me with questions.
 
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