AD-A139 076 UNCLASSIFIED MANNED EVALUATION OF THE MK-15 UBA (UNDERWATER BREATHING APPARATUS) CANIS..(U) NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY FL JL ZUMRICK JAN 84 NEDU-2-84 F/G 6/11
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....^, 7-1 DEPARTMENT OF THE NAVY NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY. FLORIDA 32407 IN «0>L» DID TO: NAVY EXPERIMENTAL DIVING UNIT REPORT NO. 2-84 MANNED EVALUATION OF THE MK-15 UBA CANISTER DURATION IN I3 C WATER USING A RESTING DIVER SCENARIO By: J. L. ZUMRICK, Jr. CDR, MC, USNR Apprved fr public release; distributin unlimited. s DTIC I ELECTED* ü MAR 19 1984 ( Submitted by: Reviewed by: Apprved by: C^JLIXJL <?Q J. L. ZUMRICK E. D. THALMANN CDR, MC, USNR CDR, MC, USN Asst. Senir Medical Officer Senir Medical Officer ßwC L ussu ssuw J FRANK E. EISSING CDR, USN Cmmanding Officer JF- -J -V
i ii iiwpiwm T- UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When D.i. Enl.r.d) REPORT DOCUMENTATION PAGE READ INSTRUCTIONS BEFORE MPLETING FORM 1. REPORT NUMBER NEDU REPORT NO. 2-84 2. QOVT ACCESSION NO. 3. RECIPIENT'S CATALOG NUMBER 4. TITLE (end Subtitle) MANNED EVALUATION OF THE MK-15 UBA CANISTER DURATION IN 13 C WATER USING A RESTING DIVER SCENARIO. 7. AUTHOROJ S. TYPE OF REPORT ft PERIOD VERED FINAL 6. PERFORMING ORG. REPORT NUMBER S. NTRACT OR GRANT NUMBERf«; J. L. ZUMRICK, Jr., CDR, MC, USNR S. PERFORMING ORGANIZATION NAME AND ADDRESS NAVY EXPERIMENTAL DIVING UNIT PANAMA CITY, FL 32407 10. PROGRAM ELEMENT. PROJECT, TASK AREA ft WORK UNIT NUMBERS M. NTROLLING OFFICE NAME AND ADDRESS 12. REPORT OATE January 1984 13. NUMBER OF PAGES 19 I«. MONITORING AGENCY NAME ft AODRESSfff dlllerent (ran Cntrlling Olllce) IS. SECURITY CLASS, (el thle reprt) IS«. UNCLASSIFIED OCCLASSIFICATION/DOWNGRADING SCHEDULE I«. DISTRIBUTION STATEMENT fi thle Rprl) Apprved fr public release; distributin unlimited. 17. DISTRIBUTION STATEMENT (l the mbetrmct entered In Blck 30, II dlllerent Item Reprt) It. SUPPLEMENTARY NOTES 19 KEY WOROS (Cntinue n rererte elde II neceeeery mnd Identity r Mck number) MK-15 Passive Diver Thermal Prtectin System(PDTPS) Clsed Circuit UBA Oxygen Cnsumptin Canister Duratin NEDU Study N. 83/42 ADSrDent \ c^2 20 ABSTRACT (Cntinue n i reeeree elde II neceeeery end Identity by blck number) ^>The ^ «absrbent canister duratin f the MK-15 clsed-circuit Underwater Breathing Apparatus (UBA) was evaluated using a resting diver scenari in 13*fC water at 65 FSW. The Passive Diver Thermal Prtectin System (PDTPS) was wrn during the study. Results demnstrate that the safe/peratinal limit f the MK-15 UBA fr a diver mainly at rest in 13 ^C water is 321 minutes. %,:::- wi EDITION OF t NOV If OBSOLETE S/N 0102-LF-014.6601 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAOE (9nen Dele Untere*) -..V
I f r ' '" ' i ABSTRACT The i absrbent canister duratin f the MK-15 clsed-circuit Underwater Breathing Apparatus (UBA) was evaluated using a resting diver scenari in 13 C water at 65 FSW. The Passive Diver Thermal Prtectin System (PDTPS) was wrn during the study. Results demnstrate that the safe peratinal limit f the MK-15 UBA fr a diver mainly at rest in 13 C water is 321 minutes. Key Wrds: MK-15 Clsed-Circuit UBA Canister Duratin i Absrbent Passive Diver Thermal Prtectin System (PDTPS) Oxygen Cnsumptin NEDU Study N. 83/42 Accessin Fr TIS~ GRA&I DT1C TAB G Unannunced D Justificatin By Distributin/^ Avallabil HT_Cdes_ livaii and/r Di»t Special M. ii
INTRODUCTION The MK-15 Underwater Breathing Apparatus (UBA) is a clsed-circuit UBA designed t supprt extended diving peratins f up t six hurs. In nrmal peratin, it autmatically maintains the inspired partial pressure f xygen at a pre-set level, usually 0.7 ± 0.05 ATM, by adding xygen t the breathing lp t replace that cnsumed by the diver. The diver's exhaled gas passes thrugh a carbn dixide absrbent canister which extracts the a prduced by the diver. Except during ascent, the breathing gases are cmpletely cntained within the breathing lp and n lsses ccur t the surrunding water. When gas leaks frm the MK-15 are minimal, the duratin f the apparatus is determined either by the xygen bttle capacity r the duratin f the * absrbent canister. Previus studies have demnstrated that the peratinal limit f the MK-15 is determined nt by the xygen bttle capacity but by the duratin f the carbn dixide absrbent canister (1). This study demnstrated a canister duratin f 117.5 minutes in 2 C (35.6 F) and 13.4 C (56.1 F) water when using a standard canister testing prtcl cnsisting f alternating perids f six minutes wrk and 4 minutes rest n an underwater pedal-mde ergmeter set at a wrk rate f 50 watts resulting in a mean V» f 1.5-2.0 t/min. The standard canister testing prtcl simulates the maximum exercise that a diver can reasnably be expected t sustain fr a prlnged perid f time. An apparatus which prvides adequate carbn dixide remval ver its required time duratin using this prtcl can reasnably be expected t
', _,, prvide adequate life supprt fr a diverse variety f dive scenaris. This prcedure, hwever, may nt adequately describe a UBA's perfrmance in a limited and specific applicatin. UBA's can be used In diving scenaris where divers may be mainly at rest, this study was undertaken t demnstrate MK-15 canister duratin under these cnditins. METHODS All dive subjects were military trained divers familiar with the pera- tin f the MK-15 UBA. Their physical characteristics are given in Table 1. All dives were cnducted in the OSF wet chamber chilled t 13.0 C (56.0 F). The chamber was pressurized t 60 FSW n air with a platfrm in the wet chamber 5 feet belw the water level, resulting in a diver depth f 65 FSW. Exercise was prvided by tw pedal-mde ergmeters (2) which were placed n the platfrm In a hrizntal attitude. This allwed tw MK-15 diver-subjects t exercise simultaneusly, thereby dubling the number f runs which culd be accmplished each day. A standby diver with cmmunicatins t the surface was ready t assist the divers during all tests. The MK-15 divers had n cmmunicatins ther than hand signals. Each diver wre the Passive Diver Thermal Prtectin System (PDTPS) which cnsisted f full lng Jhn underwear, wl scks, Thinsulate thermal undergarment with hd, dry suit uter garment with glves, and weights at the midllne (6).
The initial UBA set up and all canister changes were dne n the surface. Prir t each dive day, three MK-15 UBA's were set t maintain POi at 0.70 + 0.05 ATA. Air was used as the diluent gas. T prevent dive terminatin due t an exhausted diluent gas supply, each UBA was prvided with an umbilical air supply fr diluent gas in place f the diluent bttle. A fully-charged, rechargeable nickel-cadium battery was used fr each dive, and the canisters were freshly packed and weighed using the same batch f High Perfrmance (H.P.) S0DAS0RB (W. R. Grant & C.) thrughut all canister duratin studies. Canister effluent * and 0* gas samples were btained by small diameter (.032 in i.d.) capillary sample lines with sampling rates f 200 t 500 cc/min (STPD). A micrmetering valve at the sample rigin fr flw cntrl allwed a delay time f less than tw secnds and prvided rapid respnse t variatins in gas cmpsitin withut significant mixing in the sample line (3). The gas samples were anlayzed by either a Perkin Elmer MGA 1100 r a Chemetrn Mdel 7401 mass spectrmeter. An accuracy f ± 0.01% was btained by frequent calibratins during the experiment. The xygen bttle pressure was measured by a Validyne DP 15 Pressure Transducer equipped with a 3000 psig ± 1% diaphragm which was munted n the MK-15 UBA. This transducer was calibrated frm 0-2500 psi against a Mensr 11600 digital pressure gauge (2500 psi ± 0.04%) befre and after each study. A linear regressin f Validyne vltage versus digital pressure gauge reading was calculated by a HP-1000 cmputer. The Validyne utput vltage was then directly cnverted t punds per square inch each time the cmputer sampled. After each run, a plt f xygen bttle pressure versus time was made, and the xygen cnsumptin was estimated frm this plt, as will be described.
Once all the equipment was checked and calibrated, the divers entered the water and perfrmed the exercise sequence as shwn in Figure 1. This exercise sequence was designed t simulate missins where shrt perids f exercise are interspersed with lng perids f rest. During the exercise perids, the divers wrked against an ergmeter setting f 50 watts, at a rate f 55 rpm. The actual wrk lad perfrmed by the diver, due t the cmbined resistance f the water and thermal prtectin garment, was 25-50 watts greater than indicated. During the rest perids, the divers engaged in game tasks which kept them ccupied and essentially at rest. The dives were'terminated when either the canister effluent i exceeded 2.0% Surface Equivalent Value (SEV) (15.8 mmhg) at any time during the wrk cycles fr at least 1 minute during rest, r when 3% SEV value (22.8 mmhg) was reached at any pint during the study. These terminatin pints were chsen t ensure that a definite canister end pint culd be established that was unaffected by the diver's activity level. These * levels are greater than thse t which an peratinal diver shuld be expsed, and are acceptable nly under rigidly cntrlled circumstances where they prvide a clearly defined end pint t the study frm which an peratinal duratin can be determined. RESULTS A ttal f five canister duratins were successfully cmpleted during this study. Water temperature averaged 12.9 ± 0.2 C. The canister effluent i versus time charts fr the five tests are fund in Figures 2A-2E. Clse inspectin f these shwed shrt perids f rising i which represents the exercise perids interspersed within the lnger rest perids. After five hurs, when the six minute exercise, fur minute rest sequence was cntinuus, canister effluent i rse sharply during wrk and declined during the intervening rest perid frming a jagged sinusidal pattern. Canister 4 äp~" r.' * - -'
duratin times were determined by digitizing thse mean peak» values and then btaining the best data fit using a plynmial regressin equatin (Table 2). canister duratin was taken as the time where the regressin line crssed the 0.5% SEV (3.8 mmhg) i value. Table 2 summarizes the verall diver xygen cnsumptin (VQ ) during the study, the xygen cnsumptin during rest and exercise, pre and pst dive canister weights, and the time taken fr the canister effluent» t reach 0.5% SEV and 1.0% SEV fr each dive. Mean canister breakthrugh time was calculated t be 321 ± 25 minutes. During tw f the dive^, the divers were replaced during the rest cycle and the dive cntinued with a new diver. These changes are represented in Table 2 as Diver #3/8 and 5/10. Bth divers were replaced because f fatigue and cld. The nickel-cadmium batteries used t pwer the MK-15 had t be changed n all five tests. The average duratin f the battery was 4 hr 50 min ± 29 minutes. During lng diving peratins, an alkaline battery with significantly lnger duratin wuld be used rather than the nickel-cadmium battery. An example f xygen bttle pressure versus time is shwn in Figure 3. Tw rates f bttle pressure decline are shwn; a mre rapid decline assciated with the exercise perids, and a gradual decline assciated with the lng rest perids. In additin, the xygen decline during rest appears t be biphasics with a slightly greater rate f decline during the latter prtin f the lng rest perids. All divers reprted feeling increasingly cld and shivering during this perid which was relieved n beginning exercise.
Overall, xygen cnsumptin fr the entire study perid was calculated using the fllwing frmula which assumes n gas leaks frm the UBA ther than the knwn gas sample rates: V 0i = (&P/AT)«(V B /14.7)«[273/(T+273)]-V s «F 0i 0 where: v, AP/AT V B 14.7 T vs 0 t cnsumptin (l/min STPD) Slpe f 0* pressure plt (psl/min) 0» bttle vlume (I) psl/ata cnversin factr 0t bttle temperature ( C) UBA gas sample rate (.250 SLPM) Oxygen fractin in gas sample The average xygen cnsumptin rate during exercise was 2.24 ±.15 l/min, and.64 ±.09 l/min during rest. The verall rate f diver xygen cnsumptin ranged frm 0.8 t/min t 1.06 l/min with an average f 0.95 ±.14 l/min. Gas leaks which ccurred during the study had a minimum influence n these values since the partial pressure cf 0* In the air diluent used at 65 FSW t make up vlume was 0.63 a.. and nearly Identical t the MK-15 xygen set pint. I
T DISCUSSION In practice, canister duratin times exhibit wide variability. Unpublished bservatins during bth manned and unmanned testing at NEDU shw that small changes in i prductin rates may result in large changes in canister duratin. Mrever, additinal factrs such as ambient temperature, flw r.'ite f gas thrugh the canister, canister packing with SODASORB, and breathing patterns may affect canister duratin times. A previus study, which evaluated MK-15 canister duratins using a standard canister testing prtcl used at NEDU, reprted canister duratins which averaged 47% less than thse fund in this Study (.1). Hwever, in that study, due t the greater level f diver exertin, xygen cnsumptin and cnsequently the i prductin rates were 42% greater than in this study. Thus, variatins in the i prductin rate wuld appear t accunt fr the differences in canister duratins measured during the tw studies. I. During the previus MK-15 study, canister duratin in 2 C water was nt significantly different frm that fund in 13.4 C water. In the previus study, divers exercised mre and had similar xygen cnsumptins at the tw temperatures, indicating that cld stress did nt result in significant shivering and therefre, additinal i prductin. In this study, divers reprted being cld and experiencing intermittent shivering particularly during the latter prtin f the lng rest perids. These subjective feelings f cld were supprted by a slight increase in xygen cnsumptin as indicated by the biphasic nature f xygen bttle pressure declines during the latter prtin f the rest perids. Canister duratins in clder water are expected t be shrter using this resting diver scenari due t the increased xygen
cnsumptin frm shivering. Therefre, additinal testing is required t determine MK-15 canister duratin in 2 C water using the resting diver scenari. The designatin f a carbn dixide limit f 0.5% SEV t establish canister breakthrugh time is nt a physilgical limit, but a practical ne based n the i effluent curve and the need fr a standardized endpint. Inspired t levels f up t 2% SEV are safe t breathe withut significant detrimental physilgical effects (A). As can be seen in the figures, nce canister effluent t reaches 0.5% SEV, rapid increases in canister effluent i can be expected thereafter. The mean time fr canister effluent t reach 0.5% SEV was 321 ± 25 minutes, while it tk 368 ± 31 minutes t reach 1% SEV. If the subjects in this study are taken t represent the nrmal ppulatin f divers wh will use the MK-15, a minimum time f 306 minutes t reach 1% SEV can be expected fr 97.5% f the general ppulatin (mean minus tw standard deviatins) and 335 minutes fr 82% f the ppulatin f MK-15 divers. Therefre, it is reasnable t use the value f 321 minutes, the mean time t reach 0.5% SEV as an indicatin f canister breakthrugh since a canister effluent f 1% SEV carbn dixide is nt likely t ccur ver this slightly increased interval, and a 2% level is extremely unlikely. If must be emphasized that the value f 321 minutes applies nly t a diver wh is predminantly resting in 13 C (55 F) water. It must als be emphasized that any peratinal factr which results in an increased diver * prductin (such as a decrease in diver thermal prtectin, an increase in diver exercise level due t as equipment failure, etc.) will result in a significantly shrter canister duratin. This means that at present the.
321 min duratin time will have little peratinal applicatin until a methd is fund t d real time integratin f diver exercise rate and relate this directly t canister duratin time. Since the abve peratinal factrs must be cnsidered likely, it is advisable that equipment mdificatins t increase canister duratin be made. The gal sught by such mdificatins shuld be t prduce a canister duratin t meet missin requirements when tested using the standard NEDU canister duratin testing prcedure. When this gal is achieved, it is likely that missins will be limited by thermal prtectin cnstraints rather than his breathing apparatus. j
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2.0 MK15 CRNISTER DURRTION - TEST #1 in s 6 hi in 1.5 1.0,5-0.0 420 MK15 CRNISTER TIME IN MINUTES 2.0 MK15 CRNISTER DURRTION - TEST 2 s 1.5 1 6 en 1.0,5-0.0 300 360 420 MK15 CRNISTER TIME IN MINUTES FIGURES 2A, 2B. Canister Effluent ^ Versus Time fr Tests 1 and 2. 13
T UJ t 2.0 MK15 CRNISTER DURRTION - TEST #3 8 l 1.5-1.0 - en 5 0.0 120 1B0 240 300 360 420 MK15 CRNISTER TIME IN MINUTES UJ H 2.0 MK15 CRNISTER DURRTION - TEST #4 1.5 s ft 1.0 -.5-0.0.i,*»^**^^ 60 120 IBB 240 300 360 420 MK15 CRNISTER TIME IN MINUTES FIGURES 2C, 2D. Canister Effluent fc Versus Time fr Test 3 and U. Data representatin fr Test 3 is incmplete. 14
^^^^^^m 8.0 MK15 CRN ISTER DURRTION - TEST #5 S 1.5 1.0 -.5-0.0 U»2. 420 MK15 CRNISTER TIME IN MINUTES FIGURE 2E. Canister Effluent? Versus Time fr Tesc 5. \ 15
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pa " a ^r- REFERENCES 1. Jaggears, F.R., Thalmann, E.D.; Manned Evaluatin f the MK-15 Clsed Circuit UBA Canister Duratin at 13.4 C and 2 C. U.S. Navy Experimental Diving Unit Reprt 6-83, June 1983. James, T.W.; Mdified Cllins Pedal-Mde Ergmeter: Develpment and Medical Tests. U.S. Navy Experimental Diving Unit Reprt 1-76, June 1976. Thalmann, E.D., et al; Chamber Based System fr Physilgical Mnitring f Submerged Exercising Subjects, Undersea Bimedical Research 5:293-300, September 1978. 4. Zumrick, J.L., Thalmann, E.D.; Manned Evaluatin f Field Change #955, The Mark-11 Dry Helmet n MK-11 UBA perfrmance. U.S. Navy Experimental Diving Unit Reprt 8-81, Nvember 1981. 5. Durnin, J.V.G.A., Wnersley, J; Bdy Fat Assessed Frm Ttal Bdy Density and its Estimatin Frm Skinfld Thickness: Measurements n 481 Men and Wmen Aged Frm 16-72 Years, British Jurnal f Nutritin 32:77-97, 1974. Technical Manual - Operatins and Maintenance Instructins - Passive Diver Thermal Prtectin System (PDTPS), NAVSEA Technical Manual SS5O0-AL0MMO-010, 15 September 1983. 17 _- I -"
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