{"id":358,"date":"2010-01-09T12:17:06","date_gmt":"2010-01-09T16:17:06","guid":{"rendered":"http:\/\/www.divetalking.com\/?p=358"},"modified":"2010-01-17T09:08:07","modified_gmt":"2010-01-17T13:08:07","slug":"surface-consumption-rate-scr","status":"publish","type":"post","link":"https:\/\/www.divetalking.com\/?p=358","title":{"rendered":"Surface Consumption Rate, SCR"},"content":{"rendered":"

The examples below are NOT to be used to calculate decompression dives.
\nDo not attempt to calculate the amount of gas needed to perform
\ndecompression dives solely on the Information within this text.
\nTechnical \/ decompression diving requires proper training.<\/span><\/p>\n

\u00a0Surface Consumption Rate, SCR. SCR is the average utilization of volume of
\n\u00a0gas, air, over time. When you know your SCR, planned depth and time of a
\ndive, you can get a good idea on the amount of gas you will need to support
\nthe dive.<\/p>\n

\u00a0Get a calculator, an 80cf aluminum cylinder filled with approx. 3000 psi of
\nair, a water proof \u00a0timer, something waterproof to record your observations
\non. Find an area where 33 feet of seawater may be reached. A 35 foot deep
\narea would work best to help guide you towards staying at 33 feet for
\nten minutes.<\/p>\n

Once at the 33 foot depth, make note of your cylinders pressure. Begin
\nswimming at a comfortable pace for 10 minutes while maintaining a depth
\nof 33 feet. At the end of 10 minutes, record your cylinders pressure.<\/p>\n

\u00a0An example: You start the exercise at 33 feet with 2600 lbs of pressure.
\nAfter the 10 minute swim, your pressure is 2100 psi, meaning you spent
\n500 psi of gas after 10 minutes swimming at a comfortable pace at 33 feet.<\/p>\n

\u00a0We learned that 33 feet is 2 Atmospheres Absolute, ATA. We know this
\nby the following formula, ( ( DEPTH \/ 33 ) + 1 )<\/span>. For the example the
\nformula would read (( 33 \/ 33 ) + 1 ) = ( ( 1 ) + 1 ) = 2 ATA.<\/span><\/p>\n

\u00a0Up to this point, we know we spent 500 psi of air after a 10 minute
\ncomfortable swim at 33 feet. We get 500 psi of consumption by
\nsubtracting our ending pressure from the beginning pressure,
\n(2600 psi \u2013 2100 psi = 500 psi).<\/p>\n

To get the SCR from the information we take the amount of consumed
\ngas, 500 lbs and divide that by the ATA, 2 ( 500 psi \/ 2 ATA = 250 psi ).
\nThe\u00a0 quotient, 250 psi divided by the number of minutes you ran the
\nexercise, 10 minutes results with the amount of gas usage every
\nminute, ( 250 \/ 10 = 25 psi\/minute).
\nContinue to perform the steps above to build an average. Also change
\nthe tempo of the dive from a comfortable pace that range from a hover
\nto a fast pace, recording data each time. You can then mix and match
\ndata to formulate usage based on the type of diving you expect to perform.<\/p>\n

Let’s run through a complete example.
\nLet presume your average SCR is 30 psi\/minute using the formulas above.
\nLet’s plan a dive to 80 feet.<\/p>\n

You plan to dive to\u00a080 feet. How much gas will you need to support the
\ndive? Looking at the AIR RPD, you are allowed 29 minutes without
\nentering into decompression. We also see that we need to spend at least
\n3 minutes performing a safety stop at 15 feet. That is a minimum of 32
\nminutes of dive time. Let’s begin the calculations.<\/p>\n

80 feet is (( 80 \/ 33 ) + 1 )\u00a0= 3.42 ATA. With a SCR\u00a0of 30 psi\/min, at 80
\nfeet the consumption becomes ( 30 psi * 3.42 ) = 103 psi\/min.
\n103 * 29 = 2987 psi. Do you have enough gas to support the dive?
\nDon’t forget you have to get up to the safety stop and spend at least
\n3 minutes there.<\/p>\n

I say the answer is no. There is not enough gas to support the dive.
\nThat leads us to the next subject of volume.\u00a0 Presuming you have been
\nusing an Aluminum 80, you can’t keep adding air to the cylinder.
\nIt’s rated pressure is 3000 lbs which provides you with 80 cf of
\ngas. To make the above dive to 80 feet for 29 minutes, you need more
\ngas.\u00a0 Let’s look at using a different cylinder. One that holds more
\nvolume. This leads us into the subject of Respiratory Minute Volume,
\nRMV. See the section under training on the subject of RMV<\/a> to
\ncontinue.
\n<\/span>
\n\u00a0You now have the information necessary to calculate the amount of gas
\nneeded to support a dive to specific depth for a given amount of time.
\nYou also see why it is important to include in your log the time, depth,
\nstarting and ending pressure. The information may be used to calculate
\na need quantity of gas to support a dive. Of course, your data on SCR and
\nRMV \u00a0is as good as the data you enter into your log.<\/p>\n","protected":false},"excerpt":{"rendered":"

The examples below are NOT to be used to calculate decompression dives.
\nDo not attempt to calculate the amount of gas needed to perform
\ndecompression dives solely on the Information within this text.
\nTechnical \/ decompression diving requires proper training.
\n\u00a0Surface Consumption Rate, SCR. SCR is the average utilization of volume of
\n\u00a0gas, air, over time. When you know your SCR, planned depth and time of a
\ndive, you can get a good idea on the amount of gas you will need to support
\nthe dive.
\n\u00a0Get a calculator, an 80cf aluminum cylinder filled with approx. 3000 psi of
\nair, a water proof \u00a0timer, something waterproof to record your observations
\non. Find an area where 33 feet of seawater may be reached. A 35 foot deep
\narea would work best to help guide you towards staying at 33 feet for
\nten minutes.
\nOnce at the 33 foot depth, make note of your cylinders pressure. Begin
\nswimming at a comfortable pace for 10 minutes while …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-358","post","type-post","status-publish","format-standard","hentry","category-training"],"yoast_head":"\nSurface Consumption Rate, SCR - Divetalking<\/title>\n<meta name=\"description\" content=\"Divetalking\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.divetalking.com\/?p=358\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Surface Consumption Rate, SCR\" \/>\n<meta property=\"og:description\" content=\"Divetalking\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.divetalking.com\/?p=358\" \/>\n<meta property=\"og:site_name\" content=\"Divetalking\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/Divetalking\" \/>\n<meta property=\"article:published_time\" content=\"2010-01-09T16:17:06+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2010-01-17T13:08:07+00:00\" \/>\n<meta name=\"author\" content=\"admin\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"admin\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.divetalking.com\\\/?p=358#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.divetalking.com\\\/?p=358\"},\"author\":{\"name\":\"admin\",\"@id\":\"https:\\\/\\\/www.divetalking.com\\\/#\\\/schema\\\/person\\\/02d5721103fd9d171fcc8cfb74d80947\"},\"headline\":\"Surface Consumption Rate, SCR\",\"datePublished\":\"2010-01-09T16:17:06+00:00\",\"dateModified\":\"2010-01-17T13:08:07+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.divetalking.com\\\/?p=358\"},\"wordCount\":685,\"articleSection\":[\"Training\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.divetalking.com\\\/?p=358\",\"url\":\"https:\\\/\\\/www.divetalking.com\\\/?p=358\",\"name\":\"Surface Consumption Rate, SCR - 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