{"id":17272,"date":"2020-01-15T16:55:41","date_gmt":"2020-01-15T21:55:41","guid":{"rendered":"http:\/\/www.corrview.com\/?page_id=17272"},"modified":"2024-08-23T16:56:57","modified_gmt":"2024-08-23T20:56:57","slug":"case_history_ch-08","status":"publish","type":"page","link":"https:\/\/www.corrview.com\/case_history_ch-08","title":{"rendered":"Case History:  CH-08"},"content":{"rendered":"<h2>[modula id=&#8221;4206&#8243;]<\/h2>\n<p>&nbsp;<\/p>\n<h2 style=\"text-align: center;\"><span style=\"color: #003366;\">Filtration 101<\/span><\/h2>\n<h2 style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-4341\" src=\"http:\/\/www.corrview.com\/wp-content\/uploads\/a0201-03.gif\" alt=\"\" width=\"500\" height=\"5\" \/><\/h2>\n<table class=\" aligncenter\" style=\"width: 80%; border-collapse: collapse; border-style: none;\">\n<tbody>\n<tr>\n<td style=\"width: 100%; border-style: none;\">\n<h3 style=\"text-align: center;\"><span style=\"font-size: 20px; font-family: Arial Black, Avant Garde;\">The Most Common Mistakes of Water Filtration Representatives and HVAC Design Engineers<\/span><\/h3>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<ul>\n<li>\n<h4><span style=\"color: #800000;\">Preface<\/span><\/h4>\n<\/li>\n<\/ul>\n<p>A past client hires CorrView International, LLC to perform ultrasonic pipe testing at one of their older properties.\u00a0 The pipe was installed in the early 1950&#8217;s using extra heavy steel.\u00a0 They do not perform any form of corrosion monitoring and have used many different chemical water treatment companies throughout their history.\u00a0 The quality of their past chemical treatment is questionable.<\/p>\n<p>A common operational problem for the building is large pieces of rust which break off to produce flow restriction for the pump strainers.\u00a0 Rust has sufficiently accumulated in the chiller heads to impact their operation, and have forced mid season condenser water tube cleaning.\u00a0 Some examples of rust they have saved exceed 1 in. in diameter.\u00a0 Frequent manual removal of the pump and chiller strainer elements are required for cleaning.\u00a0 Their condenser water is also tinted a light brown color and has some turbidity.<\/p>\n<ul>\n<li>\n<h4><span style=\"color: #800000;\">Investigation<\/span><\/h4>\n<\/li>\n<\/ul>\n<p>Ultrasonic testing shows moderate corrosion activity of near 2-3 MPY, with moderate pitting activity but no serious wall loss.\u00a0 Ultrasonic testing identifies that the pipe has uniformly deteriorated down from an original 0.500 in. thickness to near or slightly below ASTM schedule 40 or standard specifications &#8211; the wall thickness that would be specified today were pipe replacement required.<\/p>\n<p>Over 65 years of service has deteriorated the pipe significantly but it still offers many decades of additional service life.\u00a0 Although building engineers are removing higher than normal volumes of rust, we explain that approximately 12-15 times more iron oxide is produced from its original volume of steel.\u00a0 The thickness of the rust, therefore, does not represent an equal amount of pipe wall loss.\u00a0 We recommend a critical review of the chemical treatment program for opportunities for improvement.\u00a0 We also recommend the installation of a water filter combined with an effective dispersing agent to loosen and remove the rust back into the water flow for capture.\u00a0 A centrifugal separator is recommended given the very large particles present.<\/p>\n<p>One year later we receive a call from the building chief engineer requesting further ultrasonic testing at the domestic cold water main galvanized steel riser.\u00a0 While on the property, we begin discussing their actions taken at the condenser water system and are told that they had installed a new water filter approximately 9 months ago.\u00a0 The filter was selected by their mechanical engineer based upon its very low sub-micron rating.<\/p>\n<p>The building chief engineer relates that the filter turned their condenser water crystal clear, but that they are still plagued with rust in their strainers.\u00a0 Further inspection shows the installation of a very popular sand filter capable of 0.6 micron removal efficiency at an approximate 120 GPM flowrate.\u00a0 The filter is located at the roof level mechanical equipment room (MER).\u00a0 Refrigeration machines are located in the basement.\u00a0 No chemical cleaning or dispersing agent has been applied as the filter manufacturer states it is unnecessary.<\/p>\n<p>The 2 in. inlet to the sand filter is located 12 o\u2019clock on the top of the 12 in. diameter horizontal condenser water return line to the cooling tower and approximately 1 ft. after a wide sweep 90\u00b0 elbow.\u00a0 Filter blowdown is discharged into a large holding \/ settling tank.\u00a0 The chief engineer relates that the filter worked great for the first few weeks and cleaned up the water as intended.\u00a0 Shortly after, however, the filter slowed to a minimal backwash.\u00a0 Although they suspect the filter is not operating correctly, service visits by the manufacturer claim it is working properly.\u00a0 There is approximately a 2 lb. coffee container size volume of rust or other debris in the backwash tank, which has never been cleaned since being installed 9 months ago.<\/p>\n<p>As installed, only the smallest particles of smallest mass can be sucked into the filter inlet line.\u00a0 Located on the top of the 12 in. diameter return pipe, the filter inlet is directly opposite where any heavier particulates would likely exist &#8211; which is obviously along the bottom.\u00a0 Located downstream immediately after a 90\u00b0 horizontal elbow further defines that any heavier rust or particulates will be forced to the outer wall of the elbow by inertia, velocity, and centrifugal force.\u00a0 In short, it is virtually impossible for this filter to provide any benefit as currently installed.<\/p>\n<p>Initially, the filter had been viewed by everyone as a tremendous success by clearing up the water.\u00a0 But in fact, the filter only removed those particles small enough to remain in solution long enough to be captured.\u00a0 The interpretation of success based upon the clarity of the water was unfortunately 100% wrong, and in reality, only those particles having no possibility of producing a flow blockage problem were removed.<\/p>\n<ul>\n<li>\n<h4><span style=\"color: #800000;\">Conclusion<\/span><\/h4>\n<\/li>\n<\/ul>\n<p>CorrView International, LLC reiterates our original recommendation that a Lakos style 12 in. full flow centrifugal filter would better control their problem but they have already expended their capital budget.\u00a0 We provide a written recommendation for the building to relocate the sand filter to the bottom of the supply riser where the pipe makes a 90\u00b0 transition from its vertical shaft location to horizontal.<\/p>\n<p>We also recommend removing the existing 12 in. elbow and replacing it with a 12 in. tee to provide a new dead leg.\u00a0 We further recommend to extend this dead end approximately 4 ft. downward and then gradually reduce and valve it to a 4 in. gate valve.\u00a0 Following the valve, the line would be then further reduced to the 2 in. size required for the filter.\u00a0 In this way, all rust particulates will be influenced by their own velocity, their inertia based upon physical size, and the force of gravity directly into this dead leg area.\u00a0 Water will continue to turn as it always has, as the particulates are captured.<\/p>\n<p>The mechanical engineer (PE) for the building contacts CorrView International, LLC to question our recommendation, and to inform us that the current location of the sand filter and choice of inlet location was not only their recommendation after significant consideration, but also the recommendation of the filter manufacturer.\u00a0 He suggests that we have provided no proof to any benefits of this filter relocation and that there is no cost justification.\u00a0 We relate other experiences with the same issue but the design engineer disagrees and holds firm against relocating the filter.<\/p>\n<p>Months later the building\u2019s chief engineer is finally successful at having the sand filter relocated.\u00a0 He contacts CorrView International, LLC to thank us for the help, and to relate that they have significantly reduced their rust deposit problem and that they are now finally finding large scale deposits in their settling tank.<\/p>\n<p><span style=\"color: #003366; font-family: Arial Black, Avant Garde;\"><strong>\u00a9 Copyright 2024 &#8211; William P. Duncan, CorrView International, LLC<\/strong><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>[modula id=&#8221;4206&#8243;] &nbsp; Filtration 101 The Most Common Mistakes of Water Filtration Representatives and HVAC Design Engineers Preface A past client hires CorrView International, LLC to perform ultrasonic pipe testing at one of their older properties.\u00a0 The pipe was installed in the early 1950&#8217;s using extra heavy steel.\u00a0 They do not perform any form of [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-17272","page","type-page","status-publish","hentry","category-casehistory"],"_links":{"self":[{"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/pages\/17272","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/comments?post=17272"}],"version-history":[{"count":0,"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/pages\/17272\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/media?parent=17272"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/categories?post=17272"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.corrview.com\/wp-json\/wp\/v2\/tags?post=17272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}