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Holt Systems

Baghouse differential pressure: get a text before the dust complaint

We fit a battery sensor on each collector and a gateway at the office. A blinded or burst bag becomes a text, not a complaint.

  • MeasuresPressure drop across the bags
  • ReportsEvery 1 to 5 minutes by radio
  • You getA text to the people you pick
Get a quote for baghouse alerts See the SMS alerts or call 07 2150 3666
Crusher alerts

  1. 9:12 pm

    Primary baghouse dP fell 38 percent in 10 min to 2.1 in. w.g. Fan running. Possible burst or loose bag.

  2. 9:42 pm

    Primary baghouse dP still low at 1.9 in. w.g. Fan running. Sent to all nominated people.

  3. 7:50 am

    Primary baghouse dP back to 3.4 in. w.g. after bag change. Normal sawtooth.

Example alerts from this system

about 6 in. w.g.

A US filter supplier reports that dP above about 6 in. w.g. is the point to plan bag replacement.

Source: Griffin Filters

about 25 days

In a 2009 NSW court case, damaged and caked bags went unreplaced for about 25 days before dust reached a neighbour.

Source: Land and Environment Court of NSW via AustLII

14 days

A sample Queensland quarry authority requires investigation within 14 days of a dust exceedance.

Source: Queensland Department of Environment, Science and Innovation

A bag lets go on Friday night and nobody looks at the gauge until Monday

Baghouse differential pressure (dP) is the pressure drop across the bags, and it tells you if the collector is doing its job. On most crushers it's a gauge on the housing that someone reads when they walk past.

Bags blind up, pulses go weak, or a bag bursts. It happens on night shift or over the weekend, and the first you hear is a dust complaint.

  • Too high: bags blinded or cleaning has stopped, so the fan works harder and pickup points lose suction.
  • Too low with the fan running: a burst or loose bag, or a leaking tubesheet seal.
  • Flat near zero: the sensing tubes have blocked and the gauge is lying.

Today versus with baghouse differential pressure alerts

TopicTodayWith monitoring
Spotting a burst bagDust at the stack, or a complaintA text within minutes of the fall
Bag changesOn the calendar or after a failureWhen the trend says so
Weekends and nightsThe gauge sits unreadThe sensor reads every few minutes

What we fit on the collector and at the office

  • Differential pressure sensor

    Reads the drop across the bags through two short tubes from the dirty and clean sides.

    0 to 10 in. w.g. range

  • Fan running input

    Reads a contact at the fan starter so a low dP only alerts when the fan is on.

    Reports on change

  • Gateway on the plant office

    Picks up every sensor by radio and sends the alerts out.

    Heartbeat check-in

  • Starlink or 4G backhaul

    Gets the text out from a pit or plant with patchy signal.

    Whichever suits your site

How baghouse differential pressure monitoring works on a crusher

Baghouse differential pressure sensed across the tubesheet Side section of a crusher-plant pulse-jet baghouse. Dirty air enters at the lower left and passes through the bags hanging from the tubesheet into the clean plenum above, where the pulse header sits. One bag is burst. Two tap tubes, one from the clean plenum and one from the dirty side, run to a battery differential pressure sensor beside the housing. The sensor sends a LoRa radio link to a gateway on the plant office. Below, a week-long trace of differential pressure in inches water gauge shows a normal sawtooth around 2 to 4, a slow ramp with no recovery that crosses the 6 and 8 inch bands, then a sudden cliff to near zero when the bag bursts. Baghouse section Clean plenum Tubesheet and bags Dirty inlet Pulse header Clean tap Dirty tap Battery dP sensor Plant office Gateway LoRa One week of dP, in. w.g. 6 in. w.g.: plan bag change 8 in. w.g.: bags blinded Normal sawtooth Ramp, no recovery Bag bursts dP falls Mon Thu Sun
Side section of a crusher plant baghouse with one burst bag. Two tap tubes, one from the clean plenum and one from the dirty side, feed a battery sensor that sends by LoRa radio to a gateway on the plant office. A week of dP shows the normal sawtooth, a slow ramp through the 6 and 8 in. w.g. bands, then a cliff when the bag bursts.
  1. 1

    Two tubes, one sensor

    Short tubes run from the dirty side and the clean plenum to a battery differential pressure sensor on the collector.

  2. 2

    Radio to the office

    The sensor sends a reading every 1 to 5 minutes by LoRaWAN radio to a gateway on the plant office.

  3. 3

    The trend, not just a number

    We watch the shape: the sawtooth, the low point climbing, or a sudden fall.

  4. 4

    A text to the right people

    The gateway sends out by 4G or Starlink and your nominated people get an SMS or email.

The same Friday night, with and without an alert

Without monitoring

  1. Fri 9:00 pmA bag bursts. The gauge needle drops. Nobody sees it.
  2. SatDust leaves the stack all weekend.
  3. Mon 6:30 amSomeone spots the dust or a neighbour rings.
  4. MonYou find out why, after the dust is already out.

With monitoring

  1. Fri 9:00 pmA bag bursts. dP falls with the fan running.
  2. Fri 9:10 pmText to maintenance and the boss.
  3. Sat 7:00 amCrusher stopped, bag found and changed.

What lands on your phone when a bag goes

Primary baghouse dP, last 12 hours

Dashboard view

dP now
1.9
Fan
Running
Low point
Dropping
1.9 2.7 3.5 Low alert, 30 percent under normal 3 pm5 pm7 pm9 pm10 pm in. w.g.
Example only. Your collector's alert levels come from its own baseline.

On a crushing and screening plant

Baghouses sit on crushers, screens and transfer points, outdoors and hard to reach. We walk each one and test the radio path, because steel housings block signal.

Pressure tapping into the housing is mechanical work. Your fabricator or a contractor we engage does it under your permits. We mount the sensor and tubing, set up the gateway and do the electrical work under QLD Electrical Contractor Licence 1513082.

Weak pulses are a common cause of a rising dP, so check compressed air leak monitoring. For the fan, see motor and fan vibration monitoring. For the rest of the plant, see conveyor bearing temperature monitoring.

Dump truck beside a stacking conveyor at a quarry stockpile
Illustrative photo. Photo: Robert So on Pexels

What it costs

We fix the price after a short scoping call or a site visit. It depends on how many collectors, how far they are from the gateway, and how the alerts get out.

Get a quote for baghouse alerts

The fixed price covers

  • A differential pressure sensor on each collector
  • Gateway and 4G or Starlink backhaul
  • Installation and electrical work under QLD Electrical Contractor Licence 1513082
  • Alert set-up, who gets the text and the order they're called
  • Ongoing support

What this alert won't do

  • dP is a hint, not an emissions measurement. A few torn bags in a big house may barely move it.
  • It reads every few minutes. It won't show single pulses and it doesn't control anything.
  • Battery sensors are indicative. A licence record or audit needs calibrated instruments.
  • Your collector controller, bag inspections, stack testing and lock-out procedures all stay in place.

With you every step

How the five stages go on a crushing plant.

  1. 1

    Discovery

    We walk each collector with maintenance, find the tap points and gauges, and test the radio path to the office.

  2. 2

    Design

    You get a fixed-price scope: sensors, gateway, backhaul, who gets the texts, and the tapping work listed separately.

  3. 3

    Build and test

    We set up the sensors, gateway and alert rules, then test sensor to SMS before anything goes to site.

  4. 4

    Install and commission

    We mount the sensors and gateway and do the electrical work under Licence 1513082, alongside your gauge.

  5. 5

    Ongoing support

    After a few weeks we set alert levels from each collector's own trend, show maintenance the alerts and stay on for support.

Why Holt Systems

We design, install and commission every system ourselves, then look after it with an ongoing support plan. Monitoring supplements the site's own control, protection, fire and safety systems; it does not replace them.

Alerts
SMS to any phone, no app
Based in
Brisbane, QLD
Electrical licence
QLD 1513082
After install
Ongoing support plans
Call
07 2150 3666

Baghouse differential pressure questions

What is a normal differential pressure for a baghouse?

It depends on the dust, bag media and collector design. Griffin Filters, a US supplier, reports a working band of about 2 to 6 in. w.g. (0.5 to 1.5 kPa). We set alerts from each collector's own baseline instead.

What does low differential pressure mean on a dust collector?

With the fan running, a sudden fall points to a burst or loose bag, a cage or clamp failure or a leaking tubesheet seal. A flat reading near zero can mean blocked sensing tubes, so we alert on that separately.

When should baghouse filter bags be replaced?

Griffin Filters reports that dP sustained above about 6 in. w.g. is the point to plan replacement, and above about 8 in. w.g. the bags are considered blinded. A low point that climbs after every pulse says the cake isn't coming off.

Can differential pressure tell me a bag has burst?

Often, but not always. One burst bag in a large house can move dP only a little. In the 2009 Young case before the NSW Land and Environment Court, 22 of 149 inspected bags had holes or tears. So we pair dP with bag and stack inspection.

Why is my dust collector pressure high after pulsing?

Common causes are weak pulses from low air pressure, failed diaphragms or solenoids, damp or sticky dust, and blinded bags. A low point that rises run after run points maintenance to the pulse system first.

Does this replace the collector controller or stack testing?

No. The controller keeps pulsing the bags, and any stack or dust monitoring your site needs carries on unchanged. The sensor adds a remote reading, a trend and an alert. It doesn't stop equipment.

Sources

  1. Baghouse Differential Pressure, Griffin Filters (US supplier)
  2. On-Demand Pulse Jet Cleaning: The Energy Savings Myth, Powder & Bulk Solids
  3. Environment Protection Authority v Causmag Ore Company Pty Ltd [2009] NSWLEC 164, Land and Environment Court of NSW via AustLII
  4. QGL02: Guideline for management of respirable dust in Queensland mineral mines and quarries, Queensland Government, Resources
  5. Environmental Authority EPPR00953513 (ERA 16), Queensland Department of Environment, Science and Innovation

Get a quote for baghouse alerts

Tell us what you need to watch and where. We confirm the sensors, gateway location and alert recipients, then give you a fixed price.

Or email hello@holtsystems.com.au

Your details are handled in accordance with our privacy policy.

  1. 1

    Tell us about the site

    A few lines on the assets, distances and what you need to know about.

  2. 2

    A call to scope it

    We confirm the sensors, gateway location and alert recipients, and whether a site visit is needed.

  3. 3

    Fixed price

    You receive a defined scope and a fixed price before any work starts.

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