What are the differences between screw blower and roots blower in purchasing?

The core differences between screw blower and roots blower are: roots = low cost, simple and reliable, constant current at medium and low pressure; Screw = high efficiency, energy saving, low noise, high pressure/continuous heavy load and long-term saving. Combine your pressure, water depth, running time, budget and noise to choose the most accurate one.

First, the principle and performance core differences (purchase must see)

1. Working principle

Roots blower: constant volume conveying (no internal compression), relying on the impeller to "push" the gas, and the pressure is determined by the back pressure of the pipe network.

Screw blower: internal compression, engagement of male and female screws, decreasing chamber volume and increasing pressure.

2. Energy efficiency (the biggest difference in electricity charges)

Roots: efficiency 50%–65%; The higher the pressure, the more wasteful the energy consumption and the higher the exhaust temperature (≈ 120 C).

Screw: efficiency 70%-85%; 20%–40% power saving under the same working condition, and low temperature rise (≈ 90 C).

Example: 15kW, 24h operation → annual power saving of screw ≈ 3000–5000 yuan.

3. Pressure and water depth adaptation

Roots: commonly used 30–80 kPa (water depth ≈ 1.5–3 meters); Over 80kPa efficiency plummeted.

Screw: 50–200 kPa (water depth 3–8m+); High efficiency under high pressure

4. Noise and vibration

Roots: 80–90dB (A), with high noise in the middle and low frequencies, which requires muffler and shock absorption.

Screw: 65–75dB (a), 10–15dB lower, with stable airflow and small vibration.

5. Air flow stability

Roots: The pulsation is large, and the aeration has a slight "sudden" feeling.

Screw: continuous and stable, uniform bubbles, minimal disturbance to fish and shrimp.

6. Maintenance and service life

Roots: simple structure; Cheap maintenance (oil change, gear change); Life span ≈ 50,000-80,000 hours

Screw: precise and small clearance; Long maintenance cycle (synthetic oil 4000 h); Life span ≈ 8–100,000 hours

7. Price (initial investment)

Roots: The same power is 30%-50% cheaper and the entry cost is low.

Screw: expensive, but it will save electricity and pay back the cost in 1-3 years.

Second, choose the key selection dimensions (direct comparison)

1. Select according to the culture depth

≤ 3m: Roots is sufficient and cost-effective.

3-5m: Screw is more energy-saving and has stable pressure.

> 5m/factory/deep-water cage: required screw (Roots is extremely power-consuming at high voltage).

2. Select by running time.

Intermittent use (< 12h/day): Roots (low cost)

24-hour continuous, high-density and year-round operation: screw (power saving+stability+less faults)

3. Choose according to noise and environment

Near residential area, sensitive to noise: screw (low noise)

Remote tangkou and noise don't matter: Roots

4. Select according to water quality/working condition

Sewage, impurities, easy to block: Roots (large gap, dirt resistance)

Clear water, seawater and factory circulating water: screw (precise, clean and stable)

5. According to the budget and payback period

Short-term/small pond/tight budget: Roots

Long-term/Datang/high-density/pursuit of annual electricity saving: screw (2-3 years return)

Iii. Suggestions on Selection of Aquaculture Scenes

Roots blower is more suitable:

Ordinary fish ponds and shrimp ponds with a water depth of 1.5-3m.

Small area, low density and limited budget

Intermittent oxygenation, less than 12 hours per day

The water quality is poor and contains many impurities.

Remote area, inconvenient maintenance

Screw blower is more suitable;

Water depth ≥ 3m, industrialized and deep-water culture.

24-hour continuous operation, high density and high yield per mu

Seawater/high salt/corrosive environment (screws are more anticorrosive)

Close to residential areas and requiring low noise.

Long-term (3 years+), pursuing power saving+less maintenance+high stability

Four, a sentence to sum up the purchase formula

Roots are selected for low-pressure shallow ponds, and screws are selected for high-pressure deep waters;

Choose roots for short-term saving and screw for long-term saving;

Choose roots for dirt resistance and cheap, and choose screws quietly and stably.