Engineering Technical Report · 2026 · REV 1.0

Hydraulic Control:
Pressure Tanks & VFDs

Technical selection and integration guide for water booster systems in medical-grade (CSSD) and industrial environments.

01

System Architectures

Pressure Tank

Static Storage

  • Hydraulic battery mechanism
  • High-differential cycling
  • Mechanical simplicity
  • Zero energy consumption (Idle)
VFD Drive

Dynamic Throttle

  • Continuous PID regulation
  • Constant pressure delivery
  • Soft-start motor protection
  • Major energy optimization
Hybrid System

Critical Grade

  • VFD for primary load
  • Small buffer for zero-flow
  • Water hammer suppression
  • CSSD / Hospital standard
02

Performance Matrix

Parameter Pressure Tank VFD Drive Hybrid (Optimal)
Pressure Stability ±2.0 bar (Oscillating) ±0.1 bar (Steady) ±0.1 bar (Steady)
Energy Efficiency Low (Full speed only) High (Cube Law) High (Cube Law)
Zero-Flow Handling Excellent Poor (Hunting) Excellent
Capital Cost SAR 1k - 4k SAR 4k - 20k SAR 6k - 30k
03

The Affinity Law

P ∝ n³
34% Power at 70% Speed
18mo Avg. ROI Period
04

Engineering Rules

01. Pre-charge Calibration

Set air pre-charge to 0.2 bar below cut-in pressure. Incorrect pre-charge leads to bladder failure and rapid pump cycling.

02. VFD Thermal Derating

In KSA ambient temps (45°C+), VFDs must be derated by 20% or installed in climate-controlled enclosures.

03. Zero-Flow Buffering

A 24L buffer tank prevents "hunting" when VFD systems face extremely low demand.

04. PID Tuning

Start with P=1.0, I=0.5. Over-aggressive P-gain causes mechanical vibration and pressure spikes.