Hertz Kompressoren HSC-D Series
Direct-coupled, fixed-speed oil-injected screw line spanning 22–315 kW with electronic control, internal Modbus and synchronized master/slave operation for up to two compressors.
Type
Oil-flooded rotary screw
Power
30–422 hp (22–315 kW)
Flow
127–1,872 cfm (3.60–53 m³/min)
Pressure
109/145/188 psig (7.5 / 10 / 13 bar)
Cooling
air-or-water
Drive
direct
Lubrication
oil-flooded
Models
HSC-D 22 – HSC-D 315 (direct-coupled, fixed speed)
Starter
Star-delta standard on most frames; check the schematic on the largest builds.
Typical applications
- Plant utility air
- Automotive and general industry
- Process air where load is steady
Specs & intervals below are from publicly published OEM literature and long-standing field practice. Torque values, exact revision-dated part numbers, and safety-critical settings vary by serial number — always cross-check the unit’s OEM manual and nameplate before ordering parts or performing service.
Fluid
Spec: Hertz screw compressor fluid per the unit manual
Change interval: 2,000–8,000 hr depending on fluid grade and duty — follow the panel counter
Wear parts
| Category | Interval | Source |
|---|---|---|
| Air filter element | 2,000 hr or on ΔP | |
| Oil filter | 2,000 hr | |
| Oil separator element | 4,000 hr | |
| Compressor fluid | Per fluid grade | |
| Coupling element (direct drive) | Inspect annually; replace on backlash or rubber breakdown | |
| Thermostatic valve element | As required on a high-temp fault |
Consumable part numbers change by revision and region — pull the current number from the OEM portal.
Preventive maintenance
Daily
- Check fluid level in sight glass at running temp
- Listen for unusual noise / vibration
- Check discharge pressure & temperature vs baseline
- Verify condensate drain function
- Log package amps if metered
Weekly
- Blow down receiver and drain traps
- Check for oil carryover at first drop leg
- Inspect for fluid or air leaks around airend and separator tank
- Verify safety valve is not weeping
Every 2,000 hr / 6 mo
- Change fluid filter
- Change air filter (or sooner per ΔP)
- Sample fluid for TAN / metals / water
- Clean cooler exterior with low-pressure air (never > 30 psi against fins)
Every 4,000 hr / 12 mo
- Change separator element
- Change fluid
- Inspect scavenge line & orifice for coking
- Check coupling / belt alignment & wear
- Torque electrical lugs to spec (typ. 45–75 in-lb #4–2/0 AWG)
Every 8,000 hr
- Rebuild inlet valve
- Rebuild minimum-pressure check valve
- Regrease or replace motor bearings per OEM interval
- Verify safety valve setpoint against gauge
Common faults & first checks
- High airend discharge temperature from cooler fouling
- Coupling element wear producing a start-up clunk
- Separator ΔP alarm at interval
- Master/slave comms dropout when the RS-485 pair is mis-terminated
Controller(s)
- Hertz Screw Compressor Controller (HSC / HSC-D / HGS panel) — Backlit alphanumeric LCD control panel with membrane keypad and status LEDs. Larger frames ship with the graphic touch-style panel. Exact panel varies by frame, build year and region — confirm against the panel label.
Strengths
- Wide 22–315 kW coverage in one control family
- Direct coupling removes belt maintenance
- Internal Modbus plus synchronized master/slave for two units
Weaknesses
- Fixed speed — poor part-load efficiency vs the VSD Frecon Plus / Impetus lines
- Documentation is distributor-gated
Field notes
Figures from the public Hertz HSC-D brochure. Larger frames add the scheduler and maintenance-history features; smaller frames may not carry every panel function.