Create app.py

app.py

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+import math
+import streamlit as st
+
+st.set_page_config(page_title="Pump Power Calculator", page_icon="💧", layout="centered")
+
+# ----------------------------
+# Helpers
+# ----------------------------
+G_SI = 9.80665  # m/s^2
+RHO_WATER_4C = 1000.0  # kg/m^3 (reference for SG)
+
+FLOW_UNITS = {
+    "m³/s": 1.0,
+    "L/s": 1e-3,
+    "L/min": 1e-3 / 60.0,
+    "m³/h": 1.0 / 3600.0,
+    "gpm (US)": 0.003785411784 / 60.0,  # 1 US gallon = 3.785411784 L
+    "ft³/s": 0.028316846592,
+}
+
+HEAD_UNITS = {
+    "m": 1.0,
+    "ft": 0.3048,
+}
+
+EFF_UNITS = {
+    "%": 0.01,
+    "fraction": 1.0,
+}
+
+def to_si_flow(value, unit):
+    return value * FLOW_UNITS[unit]
+
+def to_si_head(value, unit):
+    return value * HEAD_UNITS[unit]
+
+def to_fraction(value, unit):
+    return max(1e-6, min(0.999999, value * EFF_UNITS[unit]))
+
+def sg_to_density(sg):
+    return max(1e-6, sg) * RHO_WATER_4C
+
+def hydraulic_power_kw(rho, g, Q, H):
+    # P_h = rho * g * Q * H  [W]
+    return (rho * g * Q * H) / 1000.0
+
+def shaft_power_kw(P_h_kw, eff_frac):
+    return P_h_kw / eff_frac
+
+def kw_to_hp(kw):
+    return kw * 1.34102209  # metric HP
+
+# ----------------------------
+# UI
+# ----------------------------
+st.title("💧 Pump Power Calculator")
+st.caption("Compute hydraulic and shaft power for a centrifugal/rotodynamic pump. Supports SI & US units, any fluid via specific gravity.")
+
+with st.sidebar:
+    st.header("Inputs")
+    st.markdown("**Flow rate**")
+    Q_val = st.number_input("Flow value", min_value=0.0, value=0.05, step=0.01)
+    Q_unit = st.selectbox("Flow unit", list(FLOW_UNITS.keys()), index=0)
+
+    st.markdown("**Total dynamic head (TDH)**")
+    H_val = st.number_input("Head value", min_value=0.0, value=20.0, step=0.5)
+    H_unit = st.selectbox("Head unit", list(HEAD_UNITS.keys()), index=0)
+
+    st.markdown("**Fluid**")
+    sg = st.number_input("Specific Gravity (SG)", min_value=0.0, value=1.0, step=0.05,
+                         help="SG = ρ_fluid / ρ_water. Water ≈ 1.00, seawater ≈ 1.025, oils < 1, etc.")
+    rho_override = st.checkbox("Override with custom density (kg/m³)")
+    rho_custom = st.number_input("Custom density (kg/m³)", min_value=0.0, value=1000.0, step=10.0, disabled=not rho_override)
+
+    st.markdown("**Pump/Drive**")
+    eff_val = st.number_input("Pump efficiency", min_value=0.0, value=70.0, step=1.0)
+    eff_unit = st.selectbox("Efficiency unit", ["%", "fraction"], index=0)
+
+    st.markdown("---")
+    st.markdown("**Advanced**")
+    g_val = st.number_input("Gravity g (m/s²)", min_value=0.0, value=G_SI, step=0.001,
+                            help="Use 9.81 m/s² for standard Earth gravity.")
+    show_steps = st.checkbox("Show calculation steps", value=True)
+
+# Convert inputs to SI
+Q_si = to_si_flow(Q_val, Q_unit)            # m³/s
+H_si = to_si_head(H_val, H_unit)            # m
+eta = to_fraction(eff_val, eff_unit)        # fraction
+rho = rho_custom if rho_override else sg_to_density(sg)
+
+# Calculations
+P_h_kw = hydraulic_power_kw(rho, g_val, Q_si, H_si)
+P_shaft_kw = shaft_power_kw(P_h_kw, eta)
+P_h_hp = kw_to_hp(P_h_kw)
+P_shaft_hp = kw_to_hp(P_shaft_kw)
+
+# Output
+st.subheader("Results")
+c1, c2 = st.columns(2)
+with c1:
+    st.metric("Hydraulic Power", f"{P_h_kw:,.3f} kW", help="Power imparted to the fluid.")
+    st.metric("Hydraulic Power", f"{P_h_hp:,.3f} HP")
+with c2:
+    st.metric("Shaft Power", f"{P_shaft_kw:,.3f} kW", help="Power at the pump shaft (before motor/drive losses).")
+    st.metric("Shaft Power", f"{P_shaft_hp:,.3f} HP")
+
+st.divider()
+
+# Quick notes
+with st.expander("Assumptions & Notes", expanded=False):
+    st.markdown(
+        """
+- **Formulae**  
+  - Hydraulic power:  \n
+    \\(P_{hyd} = \\rho\\, g\\, Q\\, H\\)  
+  - Shaft power:  \n
+    \\(P_{shaft} = \\dfrac{P_{hyd}}{\\eta}\\)
+- **Units**: Internally, the app converts flow to m³/s and head to meters.
+- **Specific Gravity (SG)** converts to density by \\(\\rho = SG \\cdot 1000\\,\\text{kg/m³}\\).
+- **Efficiency** is the pump hydraulic efficiency (not motor efficiency).  
+- For a **motor** selection, you may want to add motor efficiency and a service factor.
+        """
+    )
+
+if show_steps:
+    st.subheader("Calculation Steps")
+    st.latex(r"Q_{SI} = Q \times \text{(flow unit factor)} \quad [\text{m}^3/\text{s}]")
+    st.latex(r"H_{SI} = H \times \text{(head unit factor)} \quad [\text{m}]")
+    st.latex(r"\rho = \begin{cases}"
+             r"\rho_{\text{custom}} & \text{if custom density is used} \\"
+             r"\text{SG} \times 1000 & \text{otherwise}"
+             r"\end{cases}")
+    st.latex(r"P_{hyd} = \rho \, g \, Q_{SI} \, H_{SI} \quad [\text{W}]")
+    st.latex(r"P_{shaft} = \dfrac{P_{hyd}}{\eta}")
+    with st.container(border=True):
+        st.code(
+f"""Given:
+    Flow = {Q_val} {Q_unit}  -> Q_SI = {Q_si:.6f} m³/s
+    Head = {H_val} {H_unit}  -> H_SI = {H_si:.6f} m
+    Specific Gravity = {sg:.4f}
+    Density used = {rho:.2f} kg/m³ (custom override = {rho_override})
+    g = {g_val} m/s²
+    Efficiency = {eff_val} {eff_unit} -> η = {eta:.6f}
+
+Computed:
+    Hydraulic Power = ρ·g·Q·H = {P_h_kw:.6f} kW = {P_h_hp:.6f} HP
+    Shaft Power     = P_h / η  = {P_shaft_kw:.6f} kW = {P_shaft_hp:.6f} HP
+""",
+        language="text",
+        )
+
+st.divider()
+st.caption("© Pump Power Calculator • Streamlit • No external APIs • Suitable for Hugging Face Spaces")