Semi-micro Oxygen Bombs Operating Instruction Manualfaculty.ycp.edu/~jforesma/educ/pchem/parr-bomb.pdf · Semi-Micro Oxygen Bombs 2 ... mented with the appropriate calorimeter manual

492M

1109ASemi-micro Oxygen Bombs

Operating Instruction Manual

Semi-Micro Oxygen Bombs

P a r r I n s t r u m e n t C o m p a n y2

Figures

Figure 11109A Semi-micro Oxygen Bomb — 3

Figure 2Binding Fuse to 1109A Bomb — 6

Figure 31109A Bomb Head Assembly, A530A2 — 7

Figure 41109A Semi-micro Oxygen Bomb, Electrodes — 12

Figure 51109A Semi-micro Oxygen Bomb, Cut-away View — 13

Figure 6Parts Diagram for the 1109A Manual Valve — 14

Parts Key for the 1109A Manual Valve — 15

Table of Contents

Purpose — 3

Description — 3

Utilities — 3

Operation — 3Safety — 4

Setting the Calorimeter Parameters — 4

Installing a Conversion Set — 5

Sample Preparation — 6

Preparing the Fuse — 7

Closing the Bomb — 7

Filling the Bomb with Oxygen — 8

Filling the Bucket — 8

Analyzing the Results — 9

Standardization — 9

Maintenance — 10

Parts List — 11

Drawings — 12


w w w . p a r r i n s t . c o m 3

Purpose

The Parr 1109A Semi-micro Oxygen Bomb is de-signed for small samples such as marine biology or ecological studies. It may also be used when sam-ple size is limited. These instructions will provide the user with guidelines for the safe operation and maintenance of the vessel. These instructions must be supplemented with manual 205M, Operating Instructions for the 1108 Oxygen Combustion Bomb, which contains information concerning sample preparation and other application information rel-evant to both vessel types. It should also be supple-mented with the appropriate calorimeter manual.

DescriptionThe semi-micro oxygen bomb is the smallest of the Parr oxygen bombs. This 22 mL bomb will handle samples that range from 25 to 200 milligrams, lib-erating 52 to 1200 calories when burned in oxygen, using initial pressures up to 35 atmospheres. Out-puts of up to 2400 calories can be accommodated if the sample is self-oxidizing, provided it is burned in an inert atmosphere and does not produce gas.

There are three main components to the semi-micro oxygen bomb: the cylinder, the screw cap and the head.

Utilities

• A minimum 99.5% purity oxygen source provid-ing 420 psig (3 Mpa) of pressure to the bomb is required.

• Distilled water to fill the twin-chambered bucket is preferred, however, demineralized or tap wa-ter with less than 250 ppm of dissolved solids is acceptable.

• To ignite the sample, 10 cm of NiCr fuse wire (P/N 45C10) per test is needed.

Operation

Note: The heat unit used in these instructions is the International Table (IT) Calorie, which is equal to 4.1868 absolute joules. This is the engineering unit commonly used in the fuel industry. The ther-mochemical calorie used in thermochemical studies is equal to 4.1840 absolute joules.

Note: The calorimeter should be standardized prior to analyzing a sample.

Figure 1

1109A Semi-micro Oxygen Bomb



Safety

1. Samples to be burned in the 1109A bomb may range in size from 25 to 200 milligrams, depend-ing upon the combustion characteristics of the material and the amount of the heat produced.

2. The total charge must not release more than 1200 calories and this limit must be reduced considerably if there is any reason to suspect that the test sample has explosive properties, or that large quantities of gas will be produced upon ignition.

3. Use only a fraction of the allowable sample weight when testing unfamiliar materials, which may burn either rapidly or explosively.

4. Do not charge the bomb with more oxygen than is necessary to obtain complete combustion. Do not fire the bomb if it is pressurized to more than 35 atmospheres.

5. Keep all parts of the bomb, especially the insu-lated electrode, in good repair at all times. If gas bubbles escape from the bomb while it is sub-merged in water, do not fire the charge.

6. Keep away from the top of the calorimeter for 15 seconds after firing. If the bomb should rupture, it is most likely that the resultant forces will be directed upward along the vertical axis.

7. Never use lubricants on valves or fittings in con-tact with high-pressure oxygen.

Setting the Calorimeter Parameters

1. Refer to the following manuals for further in-structions regarding the operation of the calo-rimeter.

Calorimeter Model Number Manual Number

6200 Isoperibol Calorimeter 442M6100 Compensated Jacket Calorimeter

455M

6725 Semi-micro Calorimeter 457M

2. When using the 1109A Semi-micro Oxygen Bomb in a calorimeter, the user must ensure that the correct User set up ID is set in order to obtain the appropriate operating parameters.

3. When using a 6100 or 6200 Calorimeter:a. Select“ProgramInfo&Control”.b. FromProgramInfo&Control,select“User/

FactorySettings”.c. Select“UserSetupID”.d. Press“Clear”.e. Enter“62-1107”(or“61-1107”).f. Press“Enter”.g. Press“ReloadUserDefaultSettings”andfol-

lowtheinstrumentprompts.h. Thiswillchangethejackettemperatureofthe

6200to25°C.Anywaterhandlingunitinuseshouldbesetat20to22°C.

4. When using the 6725 Semi-micro Calorimeter with the 6772 Calorimetric Thermometer:a. Select “Operating Controls”.b. From the Operating Controls menu, select

“Method of Operation”. This button will tog-gle between “Solution” and “Combustion”.

c. Select “Combustion”.d. For older models, please contact Parr for the

appropriate software.



Installing a Conversion Set

1. In order to use the semi-micro bomb in the larger Parr calorimeters, a conversion set must be installed. Contact Parr for the appropriate conversion kit for your older model calorimeter.

2. All of the parts needed to operate a semi-micro bomb in a 6200 or 6100 Calorimeter are provid-ed in the 6269A Semi-micro Conversion Kit. The kit consists of the following major parts:• 1109A Semi-micro Bomb• A twin-chambered calorimeter bucket• Two Inconel fuel capsules• A sufficient supply of alloy fuse wire• A supply of benzoic acid pellets for standard-

izing the calorimeter• A hose assembly for filling the bomb with

oxygen from the calorimeter

3. Install the bucket supporta. The A604DD twin-chambered bucket for

semi-micro operations consists of two cylin-drical chambers with connecting tubes. The larger chamber holds the semi-micro bomb on a ring support. The smaller chamber

serves as a draft tube in which the stirrer for the 6200 or 6100 Calorimeter can operate as a pump, circulating water through the con-necting tubes.

b. Unthread the Delrin feet from the bottom of the air can assembly of the calorimeter.

c. Install the bucket support and loosely replace the Delrin feet.

d. Check the position of the support with the twin-chambered bucket installed. The small-er chamber of the A604DD is positioned to-ward the front of the calorimeter and accepts the stirrer shaft.

e. Lower and raise the calorimeter lid slowly to check that the stirrer and temperature probe do not contact the bucket or bomb. Adjust the bucket support position as needed and tighten the Delrin feet to hold the bucket sup-port in place.

4. Replace the oxygen filling line and connection for the 1108 Oxygen Combustion Bomb (part number A19A16) with the filling line and con-nection for the 1109A Semi-micro Oxygen Bomb (part number A19A14).



Sample Preparation

1. The precision of calorimetric determinations can be improved by adherence to several basic practices:• Be consistent in all procedures. Use the

same equilibration periods, pre-periods, post-periods, weight ranges, temperature ranges, sampling techniques, etc. for compa-rable samples.

• Standardize the calorimeter with a set of temperature rises nearly identical to the tem-perature for the experimental sample. The energy equivalent is not absolutely constant over a range of temperature rise value.

• Carefully control the purity, moisture content and homogeneity of the samples.

• Weigh samples carefully and keep the ana-lytical balance in good condition.

2. Manual 205M, Operating Instructions for the 1108 Oxygen Combustion Bomb, contains valu-able information concerning sample preparation and analysis of the combustion products.

3. Some small samples do not burn well unless mixed with another easily burned material such as benzoic acid or mineral oil.

4. Foodstuffs and cellulosic materials are particu-larly sensitive to extremes of moisture content.a. Very dry samples do not form strong pellets

and usually burn too rapidly.b. In contrast, samples with too much moisture

are difficult to ignite.c. Tissue samples may be lyophilized, and then

formed into pellets.

5. Semi-micro samples generally burn best if compressed into ¼ inch diameter pellet, which can be prepared easily with the Parr 2812 Pellet Press. Parr offers ¼ inch diameter benzoic acid pellets for standardization, P/N 3414.

6. Place the sample in a tared fuel capsule (208AC) and weigh it to ±0.01 mg, then set the capsule aside while attaching the fuse to the bomb head.a. Some users may desire optional platinum

parts as these parts may provide for more complete combustion when used with samples that liberate less than 600 calories.

b. The platinum capsule (P/N 169AC) should always be used with a platinum fuse (P/N 45C3) and the platinum capsule support loop (P/N 165AC2).

Figure 2

Binding Fuse to 1109A Bomb



Preparing the Fuse

1. Parr offers a stand to support the head of the semi-micro oxygen bombs while attaching the fuse wire. The stand, including the ring, is part number A38A and the semi-micro adapter for holding the head is part number 533A.

2. Cut a 10-cm length of fuse wire and bend it to the hook terminals as shown below in Figure 2.

3. Catch the wire loop in a small Allen wrench and

rotate the wrench to form a five turn helical coil. The coiled wire will concentrate heat on the sample and serve also as a rigid support for holding the sample in place while handling the bomb prior to ignition. A pair of forceps may be useful for binding and forming the wire.

4. After coiling the fuse, set the sample in the cap-sule support loop and position the coil so that it bears against the charge. Some users of the semi-micro bomb have found it easier to keep the Inconel capsule (208AC) in place by lodging it between the turns of the capsule support loop. Quantitative transfer of the sample from the balance to the capsule becomes important when using this technique.

Closing the Bomb

1. Moisten the O-ring with distilled water, set the bomb head in the cup, and then thread on the screw cap. Some users will find it easier to leave the O-ring in the cup rather than on the head assembly.

2. Handle the bomb carefully during this operation so that the sample will not be disturbed. Unlike other Parr oxygen bombs, no water is placed inside the semi-micro bomb prior to ignition.

Figure 3

1109A Bomb Head Assembly, A530A2



Filling the Bomb with Oxygen

Note: Never fire the 1109A Semi-micro Oxygen bomb if it has been filled with more than 35 atmo-spheres of oxygen.

With a 6100 or 6200 Calorimeter: 1. Slide the oxygen filling assembly onto the valve

cap assembly (A168AC) until it rests against the valve cap shoulder.

2. Insert the pin wrench (10MB3) through the eye of the valve cap and open the cap one turn from the closed position. Leave the pin wrench in cap.

3. Press the “O2 Fill” key on the calorimeter. Af-ter 30 seconds, use the pin wrench to close the manual valve on the 1109A. The user can then press “Reset” and the residual pressure in the filling hose will be automatically released.

4. Remove the pin wrench and lift the filling con-nection off the valve cap assembly.

With the 1824 Oxygen Fill Connection:

Closetheneedlevalveandpressurereliefvalveontheoxygenfillingconnection;thenopentheoxygentankvalvenomorethanonequarterturnfromtheclosedposition.Attachthefillinghosetothegasinlettubeonthebombheadbypressingthecouplingontothevalvecap.Pushthecouplingdownwarduntilitrestsfirmlyagainstthecollaronthevalvecap.

Insertthepinwrench(10MB3)throughtheeyeofthevalvecapandopenthecapone-halfturnfromtheclosedposition.Leavethepinwrenchinthecap.

Openthefillingconnectionmeteringvalveslowlyandwatchthegaugeasthebombpressurerisestothedesiredfillingpressure(usually30atm,butnevermorethan35atm.).Immediatelyclosethemeteringvalveandusethepinwrenchtoclosethevalvecapontheinlettube.Releasetheresidualpressureinthefillinghosebypushingdownwardontheleverattachedtothereliefvalve.Afterthepressuregaugereturnstozero,removethepinwrenchanddetachthefillingconnectionfromthebombhead.

Filling the Bucket

The instructions below are for use with a 6100 or 6200 Calorimeter. When using a 6725 please refer to manual 592M.

1. By Mass

Place the semi-micro bomb in the twin chambered bucket and record the mass of the two items. Fill the bucket with water, which is 2 to 3 °C below the jacket temperature of the calorimeter, to a level 1/8” above the horizontal tube. Record the mass of the bomb, bucket and water. The difference between these two values is amount of water used to fill the bucket. All subsequent tests shall use this mass of water (+/- 0.05 g).

2. By Volumea. A 450 mL glass pipet (P/N 167HW3) is offered

for use with the 6510 and 1563A Water Han-dling Systems. Temperature controlled water flows continuously through the glass deliv-ery pipet and back to the tank to maintain a constant water temperature in the pipet for filling the calorimeter bucket with repeatable volumes. Flow through the pipet stops when the stopcock is opened to fill the calorimeter bucket. The pipet refills automatically when the stopcock is turned back to a closed posi-tion.

b. Alternatively, the bucket may be filled volumetrically using a bottle top dispenser capable of delivering 450 mL with sufficient precision (0.1%).

3. Transfer the bucket to the calorimeter and set it in place in the oval air can.

4. Slide one ignition connector onto the central ter-minal on the bomb head and push it downward as far as it will go. Then grasp the bomb with forceps or with a wire hook and lower it into the bucket. Slide the other connector onto the terminal inside the bucket.

5. Close the calorimeter cover and start the test. The calorimeter will automatically report the EE value or heat of combustion, as selected, at the end of the test.



Analyzing the Results

1. After obtaining a final reading; open the calorim-eter, lift the bomb out of the bucket and remove the ignition cords. Release the bomb pressure over a period of about one minute.

2. After all pressure has been released, open the bomb and examine the inside of the cup and the underside of the head for any unburned sample or soot.a. If evidence of incomplete combustion is

found, the test is not valid and will have to be repeated. (Note: In some cases it may be impossible to get an absolutely clean combustion without leaving a slight carbon smear in the bomb.)

b. If the residue is estimated to weigh less than 0.1 milligram, the test may still be acceptable since the error introduced will be well within the obtainable precision for the instrument.

3. Remove all unburned pieces of fuse wire from the bomb head.a. The fuse correction applied by the calorim-

eter is calculated as:e3 = (fuse value)(fuse multiplier)

Example:If the fuse multiplier is set to “1”, the fuse value must be entered in calories.

If the fuse value is to be entered in as length in cen-timeters and the Parr 45C10 fuse wire is being used, the fuse multiplier must be 2.3 cal / cm.

b. If platinum wire was used, collect and save the platinum scraps for recycling. Since platinum does not oxidize under bomb con-ditions, there is no calorimeter correction for its combustion, but there is finite energy in-put obtained from the electrical energy used to heat the wire. This correction amounts to 1 (IT) calorie when using Parr 45C3 Platinum Wire with a firing current obtained from the ignition circuit in the calorimeter.

4. Determine the net corrected temperature rise, T, and calculate the gross heat of combustion by substitution in the following equation:

Where:Hg = gross heat of combustion in calories per gram

W = energy equivalent of the calorimeter in calories per degree Celsius (determined as de-scribed under Standardization)f = correction for fuse in calories

5. Additional corrections for the heat of formation of nitric and sulfuric acids can be applied as de-scribed in the calorimeter manuals, but they may not be significant for most semi-micro samples. A typical value for the nitric acid corrections is 1.5 calories.

Standardization

1. The energy equivalent, W, of the calorimeter and its contents is determined by running a series of tests with a standard material, such as benzoic acid, which releases a known amount of energy.

2. The W value can then be calculated by dividing the known energy input by the corrected temper-ature rise, T. A supply of calorific grade benzoic acid in 1/4” diameter pellets is furnished for this purpose. Additional supplies can be obtained using Parr Catalog number 3414.

3. Standardize the calorimeter by running a series of tests with calorific grade benzoic acid using samples weighing between 0.18 – 0.22 grams and following the procedure described for a calorific determination. Obtain T and compute the energy equivalent as follows:

Where:m = mass of the sample in gramsf = correction for fuse in calories

4. The value, 6318, in the above equation is the heat of combustion of calorific grade benzoic acid in (IT) calories per gram. (Using the ther-mochemical calorie in thermochemistry, this value would be 6323 calories per gram). The 6200 and 6100 Calorimeter will perform these calculations for both standardizations and deter-minations automatically.



Maintenance

The Parr 1109A Semi-micro Oxygen Bomb will give long service if handled with reasonable care, but the user should remember that the bomb is subject to stress and its mechanical condition must be moni-tored. Any parts, which show a sign of deteriora-tion, should be replaced before failure occurs.

Do not fire the bomb if gas bubbles or other signs of a possible leak appear when the bomb is sub-merged in water. Disassemble the bomb and install new seals immediately.

Note: Never use lubricants on bomb parts or fittings in contact with high-pressure oxygen.

Tightening the 411A3 Terminal Nut can sometimes stop a gas leak through the central electrode; how-ever a leak in this area usually indicates that the 528A insulator has deteriorated and must be re-placed. Failure of this insulator can also result in a short circuit in the ignition system.

Parr offers a clamp which would be placed in a vice to support the head of the semi-micro oxygen bomb while servicing the unit. This part number is 534A.

Recommended Parts to Change After 500 Firings 1109A (Manual Check Valve)Part No. Key No. (p 14)

251AC 10531AJB 2659DD 13663DD 12528A 16

If there is a leak from the A168AC fitting, replace the entire fitting which includes the 160AC gasket and 238A O-ring.

Parr 1109A Oxygen Bombs are made from alloys that will withstand most corrosive gases, but halides in the presence of moisture are not well tolerated. If samples yielding appreciable amounts of these elements are burned in the 1109A bomb, the interior surfaces may be etched or corroded. This effect can be minimized by emptying and washing the bomb as soon as possible after firing. Light corrosion products and foreign matter can be removed by polishing with an abrasive cloth.

Parr provides oxygen bomb repair services for the 1109A. A factory test is recommended after 5000 firings. This includes replacing all of the seals, checking the dimensions of the cylinder, screw cap and head, hydrostatically testing the seals and proof firing the vessel using benzoic acid.

When returning a bomb to the factory, ship it to:Parr Instrument CompanyAttn: Repair Department211 53rd StreetMoline, IL 61265-1720

Include a Purchase Order to cover the cost of the repair, a person to contact (complete with a phone number) and return shipping information. Individ-ual repair parts can be ordered from any Parr dealer or direct from the factory.



Parts List

1109A Oxygen BombPart No. Description

A530A2 Head Assembly w/ Manual ValveA168AC Manual Valve Cap Assembly525A Bare Head532A Cylinder529A Screw Cap531AJB O-ring, 1 1/16 ID Buna-N23AC Electrode Hooks

AccessoriesPart No. Description

3414 0.2g benzoic acid (100 count)45C10 Fuse Wire, 10 cmA19A14 Fill Connection357HC O-ring for Fill Connection208AC Inconel Fuel Capsule169AC Platinum Capsule45C3 Platinum Fuse Wire165AC2 Platinum Capsule Support Loop165AC2GE Capsule Support Look Ni-Cr

Oxygen Fill ConnectionPart No. Description

357HC O-ring FKM



Drawings

Figure 4 – 1109A Semi-micro Oxygen Bomb, ElectrodesFigure 5 – 1109A Semi-micro Oxygen Bomb, Cut-away ViewFigure 6 – Parts Diagram for the 1109A Manual Valve

Figure 41109A Semi-micro Oxygen Bomb, Electrodes



Figure 51109A Semi-micro Oxygen Bomb, Cut-away View



Figure 6Parts Diagram for the 1109A Manual Valve



Parts Key for the 1109A Manual Valve

Revision 08/27/12

Documents

Semi-micro Oxygen Bombs Operating Instruction Manualfaculty.ycp.edu/~jforesma/educ/pchem/parr-bomb.pdf · Semi-Micro Oxygen Bombs 2 ... mented with the appropriate calorimeter manual