A soil remediation blower RFQ checklist should define complete operating conditions for SVE, air sparging, bioventing and biosparging. Airflow or pressure alone is not enough to select the blower.
The manufacturer needs to know whether the machine will extract contaminated soil gas under vacuum or inject clean air under positive pressure. Gas conditions, wellfield resistance, treatment losses and expected operating variation must also be defined. Incomplete data can lead to insufficient airflow, excessive temperature, unnecessary motor power or equipment that cannot operate safely with the extracted contaminants.
Process and Airflow Duty
Identify the intended process: soil vapor extraction (SVE), air sparging, bioventing, biosparging, multi-phase extraction (MPE) vapor service, combined air sparging and SVE, landfill or contaminated-soil gas extraction, or another vacuum or air-injection process. Each method creates a different blower duty. For combined systems, specify the vacuum and positive-pressure sides separately.
State whether the blower will operate under vacuum, positive pressure or a specifically engineered combination of both. Do not use a standard positive-pressure performance table to select vacuum service without confirming the relevant inlet and discharge conditions for the intended operating direction.
Define the required airflow at the system and well level. Provide normal airflow, minimum airflow and maximum airflow; flow per well; the number of wells operating simultaneously; expected startup and pulsed-operation flow; and any future capacity supported by a defined plan. Do not add the maximum flow of every installed well if those wells will not operate at the same time.
Every volumetric airflow value needs reference conditions. State whether it is actual volume at the blower inlet or discharge, standard volume, normal volume, free-air volume or a field measurement at a wellhead. Include the associated pressure and temperature. This matters in SVE because the blower inlet operates below atmospheric pressure.
Pressure, Gas and Site Conditions
For SVE, state the required vacuum at the wells; pressure loss through well branches, the main manifold, separator, filter and inlet silencer; minimum blower-inlet pressure; and maximum permitted vacuum. Identify whether each pressure is gauge or absolute. Maximum vacuum may occur when only a few wells are open or the inlet filter approaches its maintenance limit.
For air sparging, provide maximum groundwater depth, hydrostatic resistance, formation-entry pressure, injection-well resistance, branch and main-header losses, non-return-valve resistance, required pressure at each well, maximum allowable injection pressure and normal blower discharge pressure. Groundwater depth alone does not define blower pressure; air must also overcome soil-entry and distribution resistance.
Provide site elevation above sea level and local atmospheric pressure where available, along with indoor or outdoor installation and minimum and maximum ambient temperatures. Altitude affects atmospheric pressure, air density and motor cooling, so performance calculated for sea level should not automatically be applied to a high-altitude site.
For SVE, state normal, minimum and maximum inlet-gas temperature, seasonal variation, heating from upstream equipment, and cooling and condensation conditions. For air sparging, specify clean-air intake temperature and any compression or aftercooling arrangement. Maximum expected temperature is needed to evaluate motor power and discharge temperature.
Identify the complete expected gas composition for contaminated-gas extraction: main contaminants, normal and maximum concentrations, oxygen, water vapor, methane where applicable, hydrogen sulfide where applicable, carbon dioxide, chlorinated compounds, and other reactive or corrosive substances. A general description such as “hydrocarbon vapor” may not provide enough information for material-compatibility and safety evaluation.
Specify concentration units and provide sampling location, date, blower operating condition, active wells, whether each value is measured or estimated, and whether it represents normal or maximum conditions. Concentrations can change when a new extraction well opens or the system restarts after shutdown.
Safety, Moisture and Solids
Where flammable vapor may occur, provide lower explosive limit data, maximum expected concentration relative to the explosive limit, area classification, gas or vapor group where applicable, required temperature class, gas-monitoring requirements, emergency-shutdown philosophy and dilution-air requirements. Assess the complete blower package; selecting only a suitably rated motor is not sufficient.
Address toxicity and worker exposure by identifying toxic contaminants even when they are not flammable. Specify any need for gas-tight construction, seal-leak monitoring, equipment ventilation, fixed gas detectors, controlled sampling points, safe exhaust routing, maintenance decontamination and personal-protection procedures. A low flammable-gas reading does not demonstrate that the gas is safe to breathe.
For SVE and MPE vapor service, state relative humidity where known, expected condensate rate, maximum liquid surge, groundwater-entry possibility, free-product presence and foaming conditions. Define the moisture-separator arrangement, demister type and high-level shutdown provision. A standard roots blower should not receive liquid slugs, so the separation system must be defined before the blower is approved for the duty.
Describe expected particle type, approximate particle size, dust concentration where known, moisture content, filter type, clean-filter pressure loss, maximum allowable pressure loss and maintenance frequency. A dry, low-dust SVE stream creates different requirements from wet gas containing fine soil particles.
Wellfield, Piping and Treatment Resistance
Wellfield information should include total well count, number active at the same time, vertical or horizontal well type, well depths, screen lengths, airflow and vacuum or pressure at each well, well spacing, soil permeability and layering, seasonal groundwater levels, and pilot-test results. Pilot-test measurements provide the strongest preliminary basis for blower selection.
For pipeline sizing, describe the main-header and branch diameters, pipe lengths, number of bends, valve types, flexible connections, elevation changes, underground or above-ground installation, condensate low points, pipe materials and expected future extensions. The blower cannot compensate efficiently for an undersized or water-filled manifold.
For the moisture separator, state vessel volume, maximum gas flow, normal liquid volume, maximum surge capacity, demister pressure loss, high-level alarm, high-high-level shutdown, liquid-transfer capacity and vessel vacuum rating. Include separator pressure loss in the blower-inlet calculation.
List all filters and silencers, such as inlet filters, particle filters, coalescing elements, inlet and discharge silencers, and final exhaust filters. For each component, provide clean pressure loss, maximum acceptable pressure loss, flow rating, gas and temperature compatibility, and maintenance condition. Do not treat a filter or silencer as having zero resistance.
Identify the vapor-treatment technology, such as activated carbon, thermal oxidation, catalytic oxidation, condensation, biological treatment, chemical scrubbing or combined stages. State its position relative to the blower, normal and maximum pressure loss, permitted inlet temperature, maximum gas flow, treatment-ready interlock and failure response. Treatment resistance can determine blower discharge pressure or inlet vacuum.
Operating, Electrical and Installation Requirements
Define the operating schedule: continuous or intermittent operation, hours per day, days per week, project duration, pulsed schedule, starts per hour or day, expected seasonal or unattended operation, and whether standby capacity is required. A blower intended for continuous multi-year operation may need a different package and maintenance plan from one used for a short pilot test.
State the capacity-control method: fixed speed, variable-frequency drive (VFD), constant-pressure, constant-vacuum or constant-flow control, zoned well operation, staged blowers, manual balancing or pulsed operation. Required minimum and maximum flow must remain within the blower’s permitted speed range.
Provide electrical voltage, frequency, phase count, permitted motor-starting method, VFD requirement, applicable electrical standard, enclosure protection, hazardous-area requirements, available power and cable distance. Select the motor for the maximum credible blower load, not only the normal operating point.
Describe the installation environment, including indoor or outdoor location, ambient-temperature range, humidity, dust, rain, snow, flood risk, corrosive atmosphere, hazardous-area classification, ventilation, available space, maintenance access and foundation conditions. An outdoor package may need weather protection while retaining adequate cooling and gas ventilation.
Specify package cooling, which may use natural or forced air, water cooling, an aftercooler or acoustic-enclosure ventilation. Where cooling water is available, provide its temperature, quality and flow. Include cooling failure in control and shutdown logic.
Define noise limits by maximum permitted sound level, measurement distance and environment, daytime or nighttime limit, nearby buildings and acoustic-enclosure requirement. Silencers and acoustic enclosures add pressure-loss and heat-retention considerations, so include noise treatment in the system design.
Instrumentation, Protection and Procurement Data
List required instrumentation, which may include inlet-vacuum and discharge-pressure transmitters, inlet and discharge temperature sensors, motor-current monitoring, speed indication, vibration monitoring, gas detection, separator-level interlock, filter differential-pressure indication and a treatment-ready signal. Distinguish local indications from alarms and automatic shutdowns.
For SVE vacuum service, define requirements for a vacuum-relief valve, excessive-vacuum shutdown, high-discharge-temperature shutdown, separator high-high-level shutdown and treatment-failure interlock. For positive-pressure air injection, specify pressure-relief protection, high-pressure shutdown, a non-return valve, high-discharge-temperature shutdown and low-airflow alarm. Set relief devices according to approved equipment limits.
Choose standby capacity according to the consequence of blower failure. Options include no standby for non-critical pilot work, an installed standby blower, a portable replacement connection, duty-standby or lead-lag blowers, and separate blowers for critical zones. Standby capacity may be necessary where blower failure could cause vapor intrusion or loss of containment.
Required performance documents should state blower performance at the specified duty, operating speed, absorbed power, motor rating, predicted discharge temperature and maximum permitted pressure or vacuum. Include the general arrangement, connection sizes, instrument list, noise data, cooling and maintenance requirements, and control philosophy. Report performance at the actual installation conditions.
Before issuing the enquiry, check for common omissions: airflow without reference conditions; vacuum without atmospheric pressure; groundwater depth without formation resistance; treatment pressure loss; filter loading; gas composition; liquid-carryover risk; use of positive-pressure data for vacuum service; unexplained capacity margin; undefined minimum flow; and missing hazardous-area conditions. Resolving these points before manufacture can reduce technical and commercial risk.
Glossary
Airflow Reference Condition: The pressure, temperature and moisture basis to which a stated gas volume flow applies.
Duty Point: The required combination of flow, pressure or vacuum and operating conditions used for equipment selection.
Gas Composition: The identity and concentration of gases, vapors, moisture and contaminants in the handled stream.
Gauge Pressure: Pressure measured relative to local atmospheric pressure.
Hazardous Location: An area classified because flammable gas, vapor or combustible dust may be present in an ignitable concentration.
RFQ: A request for quotation containing the technical and commercial basis needed for a comparable supplier response.
Standby Capacity: Installed reserve capacity intended to maintain an approved duty after loss or maintenance of the operating unit.