- Email: [email protected]
An alkali metal fusion bomb
MICROCHEMICAL
JOURNAL
7,
150-152
An Alkali
(1963)
Metal
Fusion
Bomb
HOWARDJ. FRANCIS, JR. Pennsalt Chemicals Couporation,
King of Prussia, Pennsylvania
Received May
9, 1963
Many investigators have found that fusion with metallic potassium or sodium at a temperature o’f 700” C for periods of time as long as 2 hours is necessary for the decomposition of many organic halogen compounds, particularly those compounds containing fluorine or materials that, because of their physical properties, do not lend themselves to the oxygen flask type of combustion. Under these conditions, the commercially available 2.5ml nickel bomb and clamping device1 is not very long lived. Belcher and Tatlow (1) and Steyermark et al. (2) have recommended modifications that allow working at higher temperatures for extended periods of time. However, it has been our experience that the design of Belcher and Tatlow (1), due to the softness of the nickel components, does not allow for very high clamping pressures without distortion of the threads. Steyermark (2) has solved the difficulty of clamping the bomb parts together by replacing the brass clamping nut and bolt of the Parr assembly1 with ones fabricated of stainless steel; the standard Parr bomb cup and cover have been retained. An objection to this arrangement is that the Parr bomb has very thin walls and a very thin sealing flange, which do not allow for the many resurfacings which are required on continued use. An alkali metal fusion bomb has been designed using suitable materials of construction and a design which allows high clamping pressures to be obtained. Only simple machine work is required, and when refurbishing of the bomb cup and cover are required this can be done very simply by hand lapping or by refacing in a lathe. Dimensions are not critical. The outer body, clamping bar, and thrust plate are machined from Incoloy2 or type 303 free machining stainless 1 Parr Instrument Company, Moline, Illinois. Series 2300-#AlMB. 2 Registered trademark of the International Nickel Company. 150
AN ALKALI
METAL
FUSION
BOMB
151
152
HOWARD
J. FRANCIS,
JR.
steel. The bomb cup and cover are machined from pure nickel bar stock. Gaskets may be fabricated from l&gauge soft annealed copper. The clamping bolt is a s by 1 inch, 13 threads per inch, Allen head cap bolt. In use the sample plus the required amount of potassium or sodium metal is placed in the bomb cup. A gasket is prepared by heating in a Bunsen flame and then plunging into a beaker of methanol; when cool, a thin coating of Fel-Pro C-S3 is placed on both sides of the gasket. The gasket is then placed on the cover and the cover is placed in position on the cup. The stainless steel thrust plate is placed on top of the cover to protect the soft nickel when clamping. Place the entire assembly into the well of the outer body, slide the clamping bar through the slots in the side and then, holding the outer body in a vise, tighten the cap bolt which has previously had a thin coating of Fel-Pro C-5 rubbed on the threads to prevent galling. To open the bomb after fusion, first remove the cap bolt and then the bomb cup and cover from the outer body. If gentle tapping does not loosen the cover the following procedure has been found to be a simple way to open the bomb without damaging the nickel parts: Hold the bomb in a vise, and with a roll-type tubing cutter place the cutter roll so that it is centered on the copper gasket and midway between the bomb cup and cover. Start rolling the cutter around the periphery of the bomb. Slowly increase the pressure on the cutter roll by screwing in the handle of the cutter. The cover will be separated from the cup, with only the gasket being destroyed. On continued use the sealing surfaces of the cup and cover will become scored and roughened. These surfaces are then refaced in a lathe. If the cap bolt becomes galled it is discarded and replaced with a new one. REFERENCES 1. 2.
BELCHER, R., AND TATLOW, J. C., Determination of fluorine in organic compounds. Analyst 76, 593 (1951). STEYEHMARK, A., AND BIAVA, F. P., Micro-Parr bomb assembly suitable for microdetermination of fluorine in organic compounds. Anal. Chem. 30, 15791.580 (1958).
3 A high temperature anti-galling Company, Chicago 7, Illinois.
compound
obtainable
from
the Felt Products
JOURNAL
7,
150-152
An Alkali
(1963)
Metal
Fusion
Bomb
HOWARDJ. FRANCIS, JR. Pennsalt Chemicals Couporation,
King of Prussia, Pennsylvania
Received May
9, 1963
Many investigators have found that fusion with metallic potassium or sodium at a temperature o’f 700” C for periods of time as long as 2 hours is necessary for the decomposition of many organic halogen compounds, particularly those compounds containing fluorine or materials that, because of their physical properties, do not lend themselves to the oxygen flask type of combustion. Under these conditions, the commercially available 2.5ml nickel bomb and clamping device1 is not very long lived. Belcher and Tatlow (1) and Steyermark et al. (2) have recommended modifications that allow working at higher temperatures for extended periods of time. However, it has been our experience that the design of Belcher and Tatlow (1), due to the softness of the nickel components, does not allow for very high clamping pressures without distortion of the threads. Steyermark (2) has solved the difficulty of clamping the bomb parts together by replacing the brass clamping nut and bolt of the Parr assembly1 with ones fabricated of stainless steel; the standard Parr bomb cup and cover have been retained. An objection to this arrangement is that the Parr bomb has very thin walls and a very thin sealing flange, which do not allow for the many resurfacings which are required on continued use. An alkali metal fusion bomb has been designed using suitable materials of construction and a design which allows high clamping pressures to be obtained. Only simple machine work is required, and when refurbishing of the bomb cup and cover are required this can be done very simply by hand lapping or by refacing in a lathe. Dimensions are not critical. The outer body, clamping bar, and thrust plate are machined from Incoloy2 or type 303 free machining stainless 1 Parr Instrument Company, Moline, Illinois. Series 2300-#AlMB. 2 Registered trademark of the International Nickel Company. 150
AN ALKALI
METAL
FUSION
BOMB
151
152
HOWARD
J. FRANCIS,
JR.
steel. The bomb cup and cover are machined from pure nickel bar stock. Gaskets may be fabricated from l&gauge soft annealed copper. The clamping bolt is a s by 1 inch, 13 threads per inch, Allen head cap bolt. In use the sample plus the required amount of potassium or sodium metal is placed in the bomb cup. A gasket is prepared by heating in a Bunsen flame and then plunging into a beaker of methanol; when cool, a thin coating of Fel-Pro C-S3 is placed on both sides of the gasket. The gasket is then placed on the cover and the cover is placed in position on the cup. The stainless steel thrust plate is placed on top of the cover to protect the soft nickel when clamping. Place the entire assembly into the well of the outer body, slide the clamping bar through the slots in the side and then, holding the outer body in a vise, tighten the cap bolt which has previously had a thin coating of Fel-Pro C-5 rubbed on the threads to prevent galling. To open the bomb after fusion, first remove the cap bolt and then the bomb cup and cover from the outer body. If gentle tapping does not loosen the cover the following procedure has been found to be a simple way to open the bomb without damaging the nickel parts: Hold the bomb in a vise, and with a roll-type tubing cutter place the cutter roll so that it is centered on the copper gasket and midway between the bomb cup and cover. Start rolling the cutter around the periphery of the bomb. Slowly increase the pressure on the cutter roll by screwing in the handle of the cutter. The cover will be separated from the cup, with only the gasket being destroyed. On continued use the sealing surfaces of the cup and cover will become scored and roughened. These surfaces are then refaced in a lathe. If the cap bolt becomes galled it is discarded and replaced with a new one. REFERENCES 1. 2.
BELCHER, R., AND TATLOW, J. C., Determination of fluorine in organic compounds. Analyst 76, 593 (1951). STEYEHMARK, A., AND BIAVA, F. P., Micro-Parr bomb assembly suitable for microdetermination of fluorine in organic compounds. Anal. Chem. 30, 15791.580 (1958).
3 A high temperature anti-galling Company, Chicago 7, Illinois.
compound
obtainable
from
the Felt Products