<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div>Brian,</div><div>you could just hook the pump up & see if you get much pressure with just air.</div><div>However you may need to then read the specs to see if it needs water running </div><div>through it for lubrication or cooling.</div><div>I am not sure how much air you would need to pump out to give a sufficient </div><div>Vacuum to set the hatch seal. Maybe that is the first question. </div><div>If you know how much air you need to pump out then if you pumped out</div><div>water instead it would need to be the same volume.</div><div>Alan</div><div><br>On 18/04/2019, at 1:12 PM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div style="font-family:Arial, sans-serif; font-size:10pt;"><font size="2" style="font-family: Arial, sans-serif;">Hi All, </font><div style=""><font size="2" style=""><font face="Arial, sans-serif"> I have this little pressure pump for my internal ballast and I'm wondering if I could use it to pull a vacuum on my sub. I was thinking it would be nice to do before I submerge, to seal the hatch. The pump I have is a 100W 12volt pump that puts out 150psi and a flow of 8L / min. Would I need to expel water to pull the vacuum? My internal ballast is about 5 1/2 gallons . Not sure if the pump would pump air efficiently.</font></font></div><div style=""><font size="2" style=""><font face="Arial, sans-serif"><br></font></font></div><div style=""><font size="2" style=""><font face="Arial, sans-serif">Brian</font></font></div><div style=""><font size="2" style=""><font face="Arial, sans-serif"><br></font></font></div><div style=""><font size="2" style=""><font face="Arial, sans-serif"> </font></font></div></div></div></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>Personal_Submersibles mailing list</span><br><span><a href="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a></span><br><span><a href="http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a></span><br></div></blockquote></body></html>