Structurally, the regulator bodies are designed for a maximum HP supply to ambient dP of 3500 psi, if used with a DIN connection.<br><br>Design intermediate pressure (HP supply to LP / ambient delivery dP) is ~150 psi. I don't know if there is any overbalancing inherent to the Apeks designs. Performance will depend on the gases used, as flow will be density dependent, but I doubt that you'll have any problems at respiratory flow rates <200 lpm.<br><br>Sean<br><br>-------- Original Message --------<br>On Feb. 16, 2021, 14:48, via Personal_Submersibles < personal_submersibles@psubs.org> wrote:<blockquote class="protonmail_quote"><br><html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body><div class=WordSection1><p class=MsoNormal>Hi,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-GB>Anyone knows till how deep you can use a first stage (Apeks) regulator? <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB><o:p> </o:p></span></p><p class=MsoNormal><span style='mso-fareast-language:NL'>Emile D.L. van Essen<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html></div>