{"id":622,"date":"2026-06-05T12:38:53","date_gmt":"2026-06-05T07:08:53","guid":{"rendered":"https:\/\/neometrixgroup.com\/resources\/?p=622"},"modified":"2026-06-05T13:00:21","modified_gmt":"2026-06-05T07:30:21","slug":"volumetric-expansion-testing-complete-guide","status":"publish","type":"post","link":"https:\/\/neometrixgroup.com\/resources\/volumetric-expansion-testing-complete-guide\/","title":{"rendered":"What is Volumetric Expansion Testing? The Definitive Guide to Hydrostatic Gas Cylinder Testing"},"content":{"rendered":"<p>Gas cylinders \u2014 whether used in CNG vehicles, hospital oxygen systems, firefighting equipment, or hydrogen fuel cells \u2014 operate under extreme pressure every single day. Over time, that pressure causes structural fatigue. Cylinders that look perfectly fine on the outside can be dangerously weakened on the inside.<\/p>\n<p><strong>Volumetric expansion testing is the only internationally recognised method to measure that internal structural change \u2014 before a cylinder fails in the field.<\/strong><\/p>\n<p>This guide explains exactly how volumetric expansion testing works, which standards mandate it globally, and why automated systems have become the industry standard for testing facilities across the USA, UK, Europe, and the Middle East.<\/p>\n<hr \/>\n<p><img decoding=\"async\" src=\"https:\/\/neometrixgroup.com\/products\/imgs\/avet.jpg\" alt=\"Neometrix AVET System full view \u2014 automated volumetric expansion test equipment\" \/><\/p>\n<h2>What is Volumetric Expansion Testing?<\/h2>\n<p>Volumetric expansion testing \u2014 also called hydrostatic expansion testing \u2014 is a pressure-based safety test applied to high-pressure gas cylinders to measure how much the cylinder expands under pressure, and critically, how much of that expansion is permanent.<\/p>\n<p>When a cylinder is pressurised, it expands slightly. A healthy cylinder will spring back to its original volume when pressure is released. A weakened or fatigued cylinder will not fully recover \u2014 it retains some of that expansion permanently.<\/p>\n<p>That permanent deformation is the key safety indicator.<\/p>\n<p><strong>The test measures two types of expansion:<\/strong><\/p>\n<ul>\n<li><strong>Elastic expansion<\/strong> \u2014 the portion of expansion that reverses when pressure is released (normal and expected)<\/li>\n<li><strong>Permanent expansion<\/strong> \u2014 the portion that does not reverse (indicates structural weakening)<\/li>\n<\/ul>\n<p>The ratio between permanent and total expansion determines whether a cylinder is safe to continue using or must be taken out of service permanently.<\/p>\n<hr \/>\n<h2>How Does the Volumetric Expansion Test Work? (Step-by-Step)<\/h2>\n<p><img decoding=\"async\" src=\"https:\/\/neometrixgroup.com\/products\/imgs\/volum1.jpg\" alt=\"Water jacket hydrostatic test setup on Neometrix Automatic Volumetric Expansion Test System\" \/><\/p>\n<p>The standard method used globally is the water jacket hydrostatic test. Here is how the process works:<\/p>\n<p><strong>Step 1 \u2014 Fill the cylinder with water<\/strong><br \/>\nThe gas cylinder is completely filled with water and sealed. Using water instead of gas means that if the cylinder fails during testing, there is no explosive gas release \u2014 making the test inherently safe.<\/p>\n<p><strong>Step 2 \u2014 Place inside a sealed water jacket<\/strong><br \/>\nThe water-filled cylinder is placed inside a larger sealed vessel also filled with water. The volume of water in this outer jacket is precisely measured.<\/p>\n<p><strong>Step 3 \u2014 Pressurise to test pressure<\/strong><br \/>\nThe cylinder is pressurised to 1.5 times its rated working pressure \u2014 the internationally mandated test pressure under ISO 6406, DOT CFR-49, EN 1968, and IS 8451. As the cylinder expands under this pressure, it displaces water out of the outer jacket. This displaced water volume is measured precisely.<\/p>\n<p><strong>Step 4 \u2014 Release pressure and measure again<\/strong><br \/>\nAfter holding test pressure, the pressure is released. The cylinder contracts. Water flows back into the jacket \u2014 but if the cylinder has permanently expanded, slightly less water returns than was displaced.<\/p>\n<p><strong>Step 5 \u2014 Calculate permanent expansion<\/strong><br \/>\nThe permanent expansion percentage is calculated using this formula:<\/p>\n<blockquote>\n<p><strong>% Permanent Expansion = [(A \u2212 C) \u00f7 (A \u2212 B)] \u00d7 100<\/strong><\/p>\n<\/blockquote>\n<p>Where:<\/p>\n<ul>\n<li><strong>A<\/strong> = Total water displaced at test pressure<\/li>\n<li><strong>B<\/strong> = Initial water volume in the cylinder<\/li>\n<li><strong>C<\/strong> = Water returned after pressure release<\/li>\n<\/ul>\n<p><strong>Step 6 \u2014 Pass or fail decision<\/strong><\/p>\n<ul>\n<li><strong>10% or less permanent expansion<\/strong> \u2192 Cylinder PASSES. Safe for continued service.<\/li>\n<li><strong>More than 10% permanent expansion<\/strong> \u2192 Cylinder FAILS. Must be permanently decommissioned.<\/li>\n<\/ul>\n<hr \/>\n<h2>Why 1.5\u00d7 Working Pressure?<\/h2>\n<p>The test pressure of 1.5 times the cylinder&#8217;s working pressure is not arbitrary. It is derived from the safety factor mandated by pressure vessel engineering standards worldwide.<\/p>\n<p>This threshold:<\/p>\n<ul>\n<li>Reveals structural weaknesses that would not appear at normal operating pressure<\/li>\n<li>Ensures the cylinder can safely withstand pressure surges and overpressure events in real-world use<\/li>\n<li>Is the minimum required by every major international standard (ISO, DOT, EN, IS)<\/li>\n<\/ul>\n<p>A cylinder that cannot survive 1.5\u00d7 its working pressure during a controlled water-based test has no business carrying pressurised gas in the field.<\/p>\n<hr \/>\n<h2>Which Cylinders Require Volumetric Expansion Testing?<\/h2>\n<p>Virtually every category of high-pressure gas cylinder requires periodic hydrostatic volumetric expansion testing. These include:<\/p>\n<table>\n<thead>\n<tr>\n<th>Cylinder Type<\/th>\n<th>Typical Industries<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>CNG (Compressed Natural Gas) cylinders<\/td>\n<td>Automotive, transport, refuelling stations<\/td>\n<\/tr>\n<tr>\n<td>Oxygen cylinders<\/td>\n<td>Medical, aerospace, defence, industrial<\/td>\n<\/tr>\n<tr>\n<td>Hydrogen cylinders<\/td>\n<td>Green energy, fuel cell vehicles, industrial<\/td>\n<\/tr>\n<tr>\n<td>Nitrogen cylinders<\/td>\n<td>Manufacturing, aerospace, oil &amp; gas<\/td>\n<\/tr>\n<tr>\n<td>CO\u2082 cylinders<\/td>\n<td>Food &amp; beverage, fire suppression<\/td>\n<\/tr>\n<tr>\n<td>Argon cylinders<\/td>\n<td>Welding, industrial gas<\/td>\n<\/tr>\n<tr>\n<td>SCBA cylinders<\/td>\n<td>Firefighting, rescue, defence<\/td>\n<\/tr>\n<tr>\n<td>Helium cylinders<\/td>\n<td>Research, aerospace, medical<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Both <strong>metal cylinders<\/strong> (steel, aluminium) and <strong>composite cylinders<\/strong> (carbon fibre wrapped) require testing, though test parameters may vary by material and standard.<\/p>\n<hr \/>\n<h2>International Standards for Volumetric Expansion Testing<\/h2>\n<p>Different regions have their own regulatory frameworks, but the underlying test methodology is consistent. Here is a breakdown by target market:<\/p>\n<h3>United States \ud83c\uddfa\ud83c\uddf8<\/h3>\n<ul>\n<li><strong>DOT CFR-49 (Title 49, Code of Federal Regulations)<\/strong> \u2014 mandates hydrostatic requalification of all DOT-approved cylinders<\/li>\n<li><strong>CGA C-1 (Compressed Gas Association)<\/strong> \u2014 standard for periodic inspection of compressed gas cylinders<\/li>\n<li><strong>NFPA 1981<\/strong> \u2014 testing of SCBA cylinders used by fire services<\/li>\n<li>Requalification interval: typically every 5 years for most CNG and industrial cylinders<\/li>\n<\/ul>\n<h3>European Union &amp; UK \ud83c\uddec\ud83c\udde7\ud83c\udde9\ud83c\uddea<\/h3>\n<ul>\n<li><strong>EN 1968<\/strong> \u2014 European standard for periodic inspection and testing of seamless steel gas cylinders<\/li>\n<li><strong>EN ISO 6406<\/strong> \u2014 periodic inspection of seamless steel compressed gas cylinders<\/li>\n<li><strong>PED (Pressure Equipment Directive) 2014\/68\/EU<\/strong> \u2014 governs pressure vessel equipment sold in the EU<\/li>\n<li>CE marking is required for testing equipment sold in EU markets<\/li>\n<\/ul>\n<h3>Middle East \ud83c\udde6\ud83c\uddea\ud83c\uddf8\ud83c\udde6<\/h3>\n<ul>\n<li><strong>ESMA (Emirates Authority for Standardisation and Metrology)<\/strong> \u2014 UAE standards for gas cylinder testing<\/li>\n<li><strong>SASO (Saudi Standards, Metrology and Quality Organisation)<\/strong> \u2014 Saudi Arabia&#8217;s gas cylinder regulations<\/li>\n<li><strong>GCC Standardisation Organisation (GSO)<\/strong> standards apply across the Gulf Cooperation Council region<\/li>\n<\/ul>\n<h3>India \ud83c\uddee\ud83c\uddf3<\/h3>\n<ul>\n<li><strong>IS 8451<\/strong> \u2014 Indian Standard for gas cylinder testing<\/li>\n<li><strong>GOI Gas Cylinder Rules<\/strong> \u2014 Government of India mandated testing requirements<\/li>\n<li><strong>CGD (City Gas Distribution) compliance<\/strong> for CNG stations<\/li>\n<\/ul>\n<hr \/>\n<h2>Manual Testing vs Automatic Volumetric Expansion Testing \u2014 Key Differences<\/h2>\n<p>For decades, volumetric expansion testing was done manually \u2014 operators physically measuring water displacement with graduated tubes and stopwatches. That method is increasingly inadequate for modern testing facilities.<\/p>\n<table>\n<thead>\n<tr>\n<th>Factor<\/th>\n<th>Manual Testing<\/th>\n<th>Automatic AVET System<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Measurement accuracy<\/td>\n<td>\u00b12\u20135% human error<\/td>\n<td>\u00b10.1% automated precision<\/td>\n<\/tr>\n<tr>\n<td>Data recording<\/td>\n<td>Paper logbooks<\/td>\n<td>Automated digital reports<\/td>\n<\/tr>\n<tr>\n<td>Test cycle time<\/td>\n<td>20\u201340 minutes per cylinder<\/td>\n<td>8\u201315 minutes per cylinder<\/td>\n<\/tr>\n<tr>\n<td>Operator dependency<\/td>\n<td>High<\/td>\n<td>Minimal<\/td>\n<\/tr>\n<tr>\n<td>Audit trail<\/td>\n<td>Manual, prone to gaps<\/td>\n<td>Complete digital records<\/td>\n<\/tr>\n<tr>\n<td>Compliance documentation<\/td>\n<td>Manual<\/td>\n<td>Auto-generated certificates<\/td>\n<\/tr>\n<tr>\n<td>Consistency<\/td>\n<td>Variable between operators<\/td>\n<td>Consistent every cycle<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>For testing facilities processing tens or hundreds of cylinders daily \u2014 such as CNG refuelling stations, industrial gas suppliers, or military requalification centres \u2014 the productivity and accuracy difference is decisive.<\/p>\n<hr \/>\n<h2>What is an Automatic Volumetric Expansion Test System (AVET)?<\/h2>\n<p>An Automatic Volumetric Expansion Test System (AVET) is a fully integrated, computer-controlled testing station that automates the entire hydrostatic expansion test cycle \u2014 from cylinder filling and pressurisation through measurement, data logging, and pass\/fail determination.<\/p>\n<p><strong>Key components of a modern AVET system:<\/strong><\/p>\n<ul>\n<li><strong>High-precision pressure control system<\/strong> \u2014 delivers and holds exact test pressure<\/li>\n<li><strong>Self-lubricating hydraulic pump<\/strong> \u2014 no external airline lubrication required<\/li>\n<li><strong>Automated data acquisition unit<\/strong> \u2014 captures all expansion measurements in real time<\/li>\n<li><strong>Touchscreen control panel<\/strong> \u2014 operator interface for test setup and monitoring<\/li>\n<li><strong>Stainless steel frame and water jacket<\/strong> \u2014 corrosion-resistant, compact footprint<\/li>\n<li><strong>Automated report generation<\/strong> \u2014 produces compliance documentation per ISO\/DOT\/EN formats<\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"https:\/\/neometrixgroup.com\/products\/imgs\/volum2.jpg\" alt=\"AVET system control panel and pressure measurement unit by Neometrix\" \/><\/p>\n<p>The system applies no heat, flame, or spark at any stage \u2014 making it intrinsically safe for testing flammable gas cylinders including CNG and hydrogen.<\/p>\n<hr \/>\n<h2>Industries and Applications That Require AVET Systems<\/h2>\n<p><img decoding=\"async\" src=\"https:\/\/neometrixgroup.com\/products\/imgs\/volum3.jpg\" alt=\"Gas cylinder testing for CNG, oxygen, and hydrogen cylinders using Neometrix AVET system\" \/><\/p>\n<h3>Gas Cylinder Testing &amp; Requalification Facilities<\/h3>\n<p>Testing stations that requalify cylinders before refilling must demonstrate regulatory compliance. An automated system provides the audit trails and documentation that manual methods cannot reliably produce.<\/p>\n<h3>CNG Vehicle and Infrastructure Industry<\/h3>\n<p>CNG fuel cylinders in vehicles must be periodically tested per DOT, ESMA, or equivalent standards. Fleet operators and CNG station owners depend on fast, accurate testing to maintain operations without extended downtime.<\/p>\n<h3>Hydrogen and Green Energy Sector<\/h3>\n<p>The global hydrogen economy is expanding rapidly. Type III and Type IV composite hydrogen cylinders used in fuel cell vehicles require rigorous testing per ISO 15869 and related standards. Automated systems handle composite cylinders without the measurement variability of manual methods.<\/p>\n<h3>Medical and Healthcare Facilities<\/h3>\n<p>Hospital oxygen cylinders are life-critical equipment. Any cylinder failure in a clinical setting can be catastrophic. Volumetric expansion testing ensures every cylinder in service meets the highest structural integrity standards.<\/p>\n<h3>Aerospace and Defence<\/h3>\n<p>Oxygen, nitrogen, and breathing air cylinders used in military aircraft, spacecraft, and pilot life support systems are subject to the most stringent testing requirements of any sector. Automated systems provide the precision and documentation demanded by defence procurement.<\/p>\n<h3>Firefighting and Emergency Services<\/h3>\n<p>SCBA (Self-Contained Breathing Apparatus) cylinders carried by firefighters are tested to NFPA 1981 and EN 137 standards. These cylinders must never fail in a life-threatening environment.<\/p>\n<hr \/>\n<h2>How to Choose a Volumetric Expansion Test System for Your Facility<\/h2>\n<p>When evaluating AVET systems for purchase, consider these factors:<\/p>\n<p><strong>1. Pressure range<\/strong> \u2014 Does it cover your full range of cylinder working pressures (typically 200\u2013450 bar for industrial cylinders)?<\/p>\n<p><strong>2. Cylinder compatibility<\/strong> \u2014 Can it handle both metal and composite cylinders across the diameter and length range you test?<\/p>\n<p><strong>3. Standards compliance<\/strong> \u2014 Is the system certified or documented for the standards applicable in your market (DOT, EN 1968, ISO 6406, IS 8451)?<\/p>\n<p><strong>4. Data and reporting<\/strong> \u2014 Does it produce reports in formats accepted by your regulatory authority?<\/p>\n<p><strong>5. Throughput<\/strong> \u2014 How many cylinders per shift does your facility need to process?<\/p>\n<p><strong>6. Customisation<\/strong> \u2014 Can the system be configured for multi-cylinder simultaneous testing if volume demands it?<\/p>\n<p><strong>7. After-sales support<\/strong> \u2014 Is local or regional service support available in your country?<\/p>\n<hr \/>\n<h2>Neometrix Automatic Volumetric Expansion Test System<\/h2>\n<p>The Neometrix AVET System is a high-precision hydrostatic testing solution designed and manufactured in India, fully compliant with ISO 6406, EN 1968, DOT CFR-49, ASME Section VIII, and IS 8451.<\/p>\n<p><strong>Designed for:<\/strong><\/p>\n<ul>\n<li>CNG, Oxygen, Hydrogen, Nitrogen, CO\u2082, Argon, SCBA, and Helium cylinders<\/li>\n<li>Both metal and composite cylinder types<\/li>\n<li>Testing facilities from single-station setups to high-volume multi-cylinder configurations<\/li>\n<\/ul>\n<p><strong>Key design features:<\/strong><\/p>\n<ul>\n<li>Automated data acquisition with zero manual measurement errors<\/li>\n<li>Self-lubricating pump \u2014 no external air lubrication needed<\/li>\n<li>No heat, flame, or spark generation \u2014 safe for flammable gas cylinder testing<\/li>\n<li>Stainless steel frame \u2014 corrosion resistant, suitable for industrial environments<\/li>\n<li>Infinitely variable cycling speed \u2014 adaptable to different cylinder sizes<\/li>\n<li>Touchscreen PLC control with automated compliance report generation<\/li>\n<\/ul>\n<p>Neometrix has delivered testing systems to defence organisations, aerospace facilities, industrial gas suppliers, and CNG infrastructure operators across India and internationally.<\/p>\n<p><a href=\"https:\/\/neometrixgroup.com\/products\/automatic-volumetric-expansion-test-system\"><strong>\u2192 View Full Product Specifications<\/strong><\/a><br \/>\n<a href=\"https:\/\/neometrixgroup.com\/request-quote\"><strong>\u2192 Request a Quote<\/strong><\/a><br \/>\n<a href=\"https:\/\/neometrixgroup.com\/products\/pdf\/automatic-volumetric-expansion-test-system-catalog.pdf\"><strong>\u2192 Download Product Catalog<\/strong><\/a><\/p>\n<hr \/>\n<h2>Frequently Asked Questions<\/h2>\n<p><strong>Q: What is volumetric expansion testing?<\/strong><br \/>\nA: Volumetric expansion testing is a hydrostatic safety test for high-pressure gas cylinders. The cylinder is filled with water, pressurised to 1.5 times its working pressure, and the permanent vs elastic expansion is measured. Cylinders with more than 10% permanent expansion must be decommissioned.<\/p>\n<p><strong>Q: What is the pass\/fail criteria for hydrostatic volumetric expansion testing?<\/strong><br \/>\nA: A cylinder passes if permanent expansion is 10% or less of total expansion. If permanent expansion exceeds 10%, the cylinder fails and must be permanently taken out of service \u2014 it cannot be refilled or repaired.<\/p>\n<p><strong>Q: What test pressure is used in volumetric expansion testing?<\/strong><br \/>\nA: The standard test pressure is 1.5 times the cylinder&#8217;s rated working pressure. This is mandated by ISO 6406, DOT CFR-49, EN 1968, and IS 8451.<\/p>\n<p><strong>Q: How often do gas cylinders need to be tested?<\/strong><br \/>\nA: Testing frequency depends on the cylinder type and applicable standard. Under DOT CFR-49 (USA), most cylinders require requalification every 5 years. EN 1968 (Europe) also specifies 5-year intervals for most seamless steel cylinders. IS 8451 (India) specifies similar intervals. CNG vehicle cylinders typically require testing every 3\u20135 years depending on jurisdiction.<\/p>\n<p><strong>Q: What is the difference between elastic and permanent expansion?<\/strong><br \/>\nA: Elastic expansion is the increase in cylinder volume under pressure that fully reverses when pressure is released \u2014 this is normal. Permanent expansion is the volume increase that does not reverse, indicating the cylinder walls have been permanently deformed. Permanent expansion is the key safety indicator.<\/p>\n<p><strong>Q: Which standards apply to gas cylinder testing in the USA?<\/strong><br \/>\nA: In the USA, the primary standard is DOT CFR-49 (Title 49, Code of Federal Regulations). CGA C-1 (Compressed Gas Association) provides supplementary guidance. SCBA cylinders used in firefighting must also meet NFPA 1981.<\/p>\n<p><strong>Q: Which standards apply in Europe?<\/strong><br \/>\nA: EN 1968 and EN ISO 6406 are the primary European standards for periodic inspection and testing of compressed gas cylinders. Equipment sold in the EU must comply with the Pressure Equipment Directive (PED) 2014\/68\/EU and typically requires CE marking.<\/p>\n<p><strong>Q: Can the Neometrix AVET system test composite (carbon fibre) cylinders?<\/strong><br \/>\nA: Yes. The Neometrix AVET system is designed to test both metal cylinders (steel and aluminium) and composite cylinders (carbon fibre wrapped), which are increasingly used in CNG vehicles, hydrogen fuel cell applications, and SCBA equipment.<\/p>\n<p><strong>Q: What is an Automatic Volumetric Expansion Test System (AVET)?<\/strong><br \/>\nA: An AVET is a fully automated hydrostatic test station that performs the complete volumetric expansion test cycle \u2014 pressurisation, measurement, data logging, and compliance report generation \u2014 without manual measurement. It eliminates human error, improves throughput, and produces digital audit trails for regulatory compliance.<\/p>\n<p><strong>Q: What industries require volumetric expansion testing?<\/strong><br \/>\nA: Industries that require gas cylinder volumetric expansion testing include automotive and CNG transport, industrial gas manufacturing and distribution, medical oxygen supply, aerospace and defence, firefighting and emergency services, hydrogen and green energy, and oil and gas.<\/p>\n<p><strong>Q: Is water jacket hydrostatic testing safe for hydrogen and CNG cylinders?<\/strong><br \/>\nA: Yes. The water jacket method is specifically designed for safe testing of cylinders that carry flammable gases. Because the cylinder is filled with water (not gas) during testing, there is no risk of explosion or fire. The Neometrix AVET system generates no heat, flame, or spark at any stage of the process.<\/p>\n<p><strong>Q: What documentation does the AVET system produce for compliance?<\/strong><br \/>\nA: The Neometrix AVET system generates automated test reports including cylinder identification, test pressure applied, total expansion measured, permanent expansion measured, percentage permanent expansion, pass\/fail result, and test date \u2014 in formats suitable for ISO, DOT, and EN compliance documentation.<\/p>\n<hr \/>\n<p><em>Neometrix Defence Limited is a Noida-based engineering solutions company with 20+ years of experience designing and manufacturing custom test equipment for defence, aerospace, gas, and industrial sectors. All Neometrix systems are Made in India, DRDO-compliant, and ISO certified.<\/em><\/p>\n<p><em>For international enquiries regarding the AVET system, contact: <a href=\"mailto:contact@neometrixgroup.com\">contact@neometrixgroup.com<\/a> | +91-7777-876-876<\/em><\/p>\n<p><strong>Gas Cylinder Testing Equipment for USA, UK, Europe &amp; the Middle East:<\/strong> Neometrix AVET systems are deployed at certified testing stations in the United States (DOT CFR-49), United Kingdom (HSE), European Union (EN 1968, PED), and Middle East (ESMA\/SASO). We supply to testing facilities across UAE, Saudi Arabia, Germany, France, and the USA. Global commissioning and after-sales support is available.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Gas cylinders \u2014 whether used in CNG vehicles, hospital oxygen systems, firefighting equipment, or hydrogen fuel cells \u2014 operate under extreme pressure every single day. Over time, that pressure causes structural fatigue. Cylinders that look perfectly fine on the outside can be dangerously weakened on the inside. Volumetric expansion testing is the only internationally recognised [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":623,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[22,21,19,53,36,30,50,18,33,20,49,34,55,17],"class_list":["post-622","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-gas-cylinder-testing","tag-avet-system","tag-cng-cylinder-testing","tag-gas-cylinder-testing","tag-gas-cylinder-testing-middle-east","tag-gas-cylinder-testing-uae","tag-gas-cylinder-testing-uk","tag-gas-cylinder-testing-usa","tag-hydrostatic-testing","tag-hydrostatic-testing-europe","tag-iso-6406","tag-iso-certified-test-equipment","tag-neometrix-india","tag-test-equipment-export-india","tag-volumetric-expansion-testing"],"blocksy_meta":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.3.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>What is Volumetric Expansion Testing? 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