{"id":550,"date":"2026-10-21T12:44:19","date_gmt":"2026-10-21T04:44:19","guid":{"rendered":"http:\/\/www.jehadcreation.com\/blog\/?p=550"},"modified":"2026-10-21T12:44:19","modified_gmt":"2026-10-21T04:44:19","slug":"how-to-measure-the-noise-level-of-a-double-screw-pump-4596-34b399","status":"publish","type":"post","link":"http:\/\/www.jehadcreation.com\/blog\/2026\/10\/21\/how-to-measure-the-noise-level-of-a-double-screw-pump-4596-34b399\/","title":{"rendered":"How to measure the noise level of a double screw pump?"},"content":{"rendered":"

Hey guys, if you\u2019ve ever worked with double screw pumps (you know, the workhorses for moving everything from lubricants to food-grade syrups or even heavy crude oil), you\u2019ve probably ran into that annoying noise issue. Like, one day it\u2019s humming along fine, the next it\u2019s sounding like a jet engine idling right next to your control room \u2013 and suddenly no one\u2019s happy. As a double screw pump supplier, I get this question all the time: \u201cHow the hell do I actually measure the noise level of these pumps correctly?\u201d It\u2019s not as simple as just grabbing a random decibel meter and pointing it, right? Let\u2019s break this down the way I actually do it for my clients, no fancy jargon that makes your eyes glaze over. Double Screw Pump<\/a><\/p>\n

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First, let\u2019s cut through the confusion: noise level measurement for double screw pumps isn\u2019t a DIY trick you can wing in 10 minutes. These pumps are precision built, but their noise comes from a handful of specific places \u2013 the rotating screws meshing, fluid turbulence in the chambers, even vibration from the base or pipes attached. Mess up the measurement setup, and you\u2019ll get a number that\u2019s way off, leading to you buying unnecessary noise dampeners or missing a real issue that\u2019s gonna blow up later.<\/p>\n

Let\u2019s start with the basics of gear before you even pull out the meter. I\u2019ve seen so many guys skip this part and mess the whole test. First, you need a decent sound level meter (SLM) \u2013 forget the $20 ones from the hardware store for this. We\u2019re talking about a Class 1 SLM, the kind that\u2019s calibrated for industrial use, not just your weekend concert checks. Class 1 means it\u2019s accurate within like \u00b10.5 dB, which is critical because a 2 dB difference is the line between \u201cnormal operation\u201d and \u201csomething\u2019s broken.\u201d Also, you need a calibrator \u2013 that little wand that blasts a known 94 dB or 114 dB tone. You calibrate your SLM before every single test, no exceptions. I once had a client skip calibration, got a reading 8 dB higher than actual, and spent $2k on acoustic panels that did nothing. Oops.<\/p>\n

Next, the test setup. This is where most people go wrong. First, the pump has to be running under actual working conditions \u2013 not the half-load test run the warehouse does when it ships. If it\u2019s a pump going into a refinery moving heavy oil, you run it with that exact oil, at the exact flow rate and pressure it\u2019ll see in the field. No water testing here \u2013 fluid viscosity changes vibration and noise big time. Also, let the pump warm up for at least 30 minutes before testing. New pumps are tight when they\u2019re cold, so they\u2019ll hum louder until the oil heats up and lubricates the screws properly. I always tell my field techs to set a timer \u2013 no skipping warm-up, ever.<\/p>\n

Now, the environment. You can\u2019t test a pump in a big empty room with concrete walls, because those will reflect sound and make the reading higher. Ideally, you test it in a semi-reverberant space, or even better, outdoors on a flat, hard surface at least 10 feet away from any other walls or equipment. Also, you have to make sure there\u2019s no background noise masking the pump\u2019s sound. If the AC unit is blowing at 50 dB, that\u2019ll throw off your pump reading if it\u2019s only at 65 dB. So, you calculate the background noise: if background is more than 10 dB lower than the pump\u2019s noise, it\u2019s fine. If it\u2019s less, you have to subtract it using this simple math: take the total measured noise, subtract a correction factor based on the difference. For example, if total is 70 dB and background is 63 dB (difference of 7 dB), you subtract 0.8 dB, so your pump noise is like 69.2 dB. Don\u2019t stress the exact math \u2013 just remember: background noise matters, and if it\u2019s too loud, pick another time or spot to test.<\/p>\n

Now, the actual measurement points. This is specific to double screw pumps, because their noise isn\u2019t evenly distributed around the unit. The two loudest spots are usually the inlet\/outlet ports (turbulence from fluid moving through those) and the gear end (where the motor drives the screws \u2013 that\u2019s the meshing noise you hear most). The standard we use (ISO 10816-7, but I\u2019ll explain it like normal people) is to take measurements at 4 key points: 1 foot away from the pump\u2019s centerline, at 0\u00b0, 90\u00b0, 180\u00b0, and 270\u00b0 around the unit. Wait, why? Because the outlet might be facing east, and if you point the meter west, you\u2019re picking up less noise from the high-pressure fluid exiting. Also, take readings at both the gear end and the pump head end, because sometimes wear on the screws will make the pump head quieter but the gears noisier. Oh, and don\u2019t hold the meter right next to the pipes \u2013 pipe vibration amplifies noise, so keep it 12 inches away from the pump\u2019s casing, not the connected hoses or pipes.<\/p>\n

Another thing: time weighting. Most SLMs have a \u201cfast\u201d and \u201cslow\u201d setting. For double screw pumps, use fast (125 ms) because these pumps have periodic noise from the screws meshing, so slow will average it out and hide spikes that mean something\u2019s wrong. Also, frequency weighting \u2013 use A-weighting, not C or Z. A-weighting matches how human ears hear noise, so it\u2019s the standard for industrial pump noise. C-weighting is for super low-frequency noise that you can feel but barely hear, so that\u2019s not what you want here.<\/p>\n

Wait, let\u2019s talk about what\u2019s a \u201cnormal\u201d noise level for a double screw pump, because that\u2019s the whole point of measuring. From what I\u2019ve tested with my pumps, a brand new double screw pump running at rated flow and pressure will be between 65 dB and 80 dB, depending on size. Small pumps (for food and beverage, 1-5 gpm) are around 65-70 dB, big ones for oil and gas (500+ gpm) are 75-80 dB. If it\u2019s over 85 dB, that\u2019s a red flag \u2013 something\u2019s wrong. Common issues: misaligned motor or pump base, worn screw rotors, bad gear oil, or even a blockage in the inlet causing turbulence. I had a client last year who called saying his pump was at 90 dB \u2013 we ran the test and found a chunk of debris stuck in the inlet, causing cavitation. Fix that, and noise dropped 15 dB in 10 minutes. Game changer.<\/p>\n

Also, keep a log. I tell every single one of my clients to write down every measurement: date, pump model, fluid type, flow rate, pressure, temperature, background noise, all the readings from the 4 points. That way, you can track changes over time. If the noise creeps up 5 dB over 6 months, that\u2019s a warning sign before it turns into a catastrophic failure. I had another client who skipped logging, and his pump ran for 2 years with a small screw wear that turned into a full rotor replacement \u2013 cost him $15k, plus downtime. Don\u2019t be that guy.<\/p>\n

Wait, can you measure noise in the field without a Class 1 SLM? Yeah, if you don\u2019t have one, but it\u2019s less accurate. But if you\u2019re troubleshooting, you can do a quick check: stand 3 feet away, if you have to raise your voice to talk over it, that\u2019s over 75 dB. If it\u2019s making a rattling or grinding sound instead of a hum, that\u2019s definitely abnormal. But for official compliance (like OSHA limits, which are 85 dB for 8 hours of exposure), you need the proper gear. OSHA has specific rules for industrial noise, so make sure you\u2019re checking that too \u2013 high noise levels aren\u2019t just annoying, they\u2019re a liability.<\/p>\n

Let me also address a common myth: double screw pumps aren\u2019t as loud as gear pumps, right? Yeah, that\u2019s true when they\u2019re working right. Gear pumps have that high-pitched whine that can hit 90 dB if worn, but a well-meshed double screw pump runs smoother, so lower noise. That\u2019s one of the reasons my clients love them \u2013 less noise means a better working environment, no need for extra ear protection. But you still have to measure it to confirm it\u2019s actually running like it should.<\/p>\n

Another pro tip from my team: if your pump is installed with a flexible coupling between the motor and pump, make sure you\u2019re not measuring the motor\u2019s noise instead of the pump\u2019s. If the SLM is picking up more noise from the motor, you\u2019ll get a higher reading that has nothing to do with the pump itself. So, when you do the measurement, you can turn off the motor for 10 seconds (safely, after bringing the pump to a stop in a controlled way) to get a baseline of motor noise, then subtract that from your total to get pure pump noise.<\/p>\n

Wait, let\u2019s recap all the steps so it\u2019s easy to follow, no skipping:<\/p>\n

    \n
  1. Calibrate your Class 1 SLM with a certified calibrator right before testing. No exceptions.<\/li>\n
  2. Prep the pump: run it at 100% rated flow\/pressure with its actual working fluid, warm up for 30+ minutes.<\/li>\n
  3. Control background noise: make sure it\u2019s at least 10 dB lower than the pump\u2019s noise. If not, adjust or subtract background.<\/li>\n
  4. Test points: 4 points around the pump, 1 foot away from casing, 12 inches from pipes, measure both gear and pump head ends.<\/li>\n
  5. Settings: A-weighting, fast time weighting, record for at least 10 seconds per point to catch any spikes.<\/li>\n
  6. Log everything, compare to baseline for future checks.<\/li>\n<\/ol>\n

    Now, if you\u2019re not sure how to do this, or you need help measuring noise for your double screw pump (whether it\u2019s troubleshooting an old one or verifying a new pump you just got), hit me up. As a double screw pump supplier, I work with clients all over, helping them with noise testing, maintenance, and even custom pumps for specific noise requirements. We can walk through the process together, or if you send me your pump specs and operating conditions, I can even give you a baseline noise level to compare your measurements against. No pressure, just honest help for anyone working with these pumps.<\/p>\n

    <\/p>\n

    And for anyone new here, trust me \u2013 measuring noise isn\u2019t just a box to tick for compliance. It\u2019s the easiest way to catch a problem early, before it turns into a huge, expensive mess. I\u2019ve seen way too many pumps fail because of unaddressed noise issues, and half of those could\u2019ve been fixed with a 10-minute noise test. So take the time to do it right, keep that log, and you\u2019ll save yourself a ton of headaches down the line.<\/p>\n

    Progressive Cavity Pump<\/a> References:
    \nISO 10816-7: Mechanical vibration \u2013 Evaluation of machine vibration by measurements on non-rotating parts \u2013 Part 7: Rotodynamic pumps for industrial applications, including measurements on rotating parts
    \nOSHA 29 CFR 1910.95: Occupational noise exposure
    \nANSI S1.4: Specification for Sound Level Meters, Part 1: General Purposes<\/p>\n

    \n

    DEPAMU (Hangzhou) Pumps Technology Co., Ltd.<\/a><\/p>\n

    Address: No. 658, 20th Street, Hangzhou Economic & Technological Development Zone, Hangzhou City, Zhejiang Province, China
    E-mail: international@depamu.com
    WebSite:     https:\/\/www.depamupumps.com\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey guys, if you\u2019ve ever worked with double screw pumps (you know, the workhorses for moving … How to measure the noise level of a double screw pump?<\/span>Read more<\/a><\/p>\n","protected":false},"author":321,"featured_media":550,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[513],"class_list":["post-550","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-double-screw-pump-44a0-356355"],"_links":{"self":[{"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/posts\/550","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/users\/321"}],"replies":[{"embeddable":true,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/comments?post=550"}],"version-history":[{"count":0,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/posts\/550\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/posts\/550"}],"wp:attachment":[{"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/media?parent=550"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/categories?post=550"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.jehadcreation.com\/blog\/wp-json\/wp\/v2\/tags?post=550"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}