Here&#x27;s an EPA document which shows some pictures, look at page 2 for the unit the OP has.<p><a href="http:&#x2F;&#x2F;www.epa.gov&#x2F;mercury&#x2F;pdfs&#x2F;EPA-905-F-11-008.pdf" rel="nofollow">http:&#x2F;&#x2F;www.epa.gov&#x2F;mercury&#x2F;pdfs&#x2F;EPA-905-F-11-008.pdf</a>